There is not a more overused word in fantasy football than "sleeper."

The classic fantasy sleeper—the player who comes from nowhere to explode into prominence—is more myth than reality. Most of the popular sleeper picks are mentioned so often that they can't be called "sleepers."

Still, production relative to cost means more to a fantasy owner than just the production itself. If you can get fourth-round value from a seventh-round pick, that's good. If you can get it from a 14th-round pick—well, those are the sorts of selections that win leagues.

We're looking for players drafted as backups who can become fantasy starters. We're focusing on ones outside the top 12 quarterbacks and tight ends, top 24 running backs and top 36 wideouts.

With those caveats in mind, and using the average-draft-position data at Football Diehards, here's a look at 25 undervalued fantasy assets who should be on your radar.

Honorable Mentions

OK, maybe we've got a few more than 25.

These players didn't quite make the cut, but that doesn't mean they aren't still worth a late look of draft day.

Consider it a bonus.

Dwayne Allen, New England Patriots (ADP: TE25)

Yes, Allen will be the clear second-fiddle to Rob Gronkowski at tight end. But in case you haven't noticed, Gronkowski has a history of getting nicked up. In the fantasy playoffs in 2016 (Weeks 14-16), with Gronk sidelined by yet another injury, Martellus Bennett was a top-10 fantasy producer at the position as New England's lead tight end.

Mike Gillislee, New England Patriots (ADP: RB35)

Gillislee is the most likely candidate in Beantown to be nominal "lead" back for the Pats, and if I had any faith he'd get a consistent workload in 2017, he'd be ranked much higher after averaging 5.7 yards per carry last season. But putting too much faith in any one member of a crowded Patriots backfield is just begging to be disappointed.

Mike Glennon, Chicago Bears (ADP: QB30)

Stop giving me that look like I just handed you a four-day-old tuna melt (the official sandwich of the 2017 Chicago Bears). No, Glennon isn't an especially good quarterback. And the Bears have the makings of being one of the NFL's worst teams in 2017. But in two-QB or "superflex" leagues Glennon could have more than a little value while playing catch-up every Sunday.

Brian Hoyer, San Francisco 49ers (ADP: QB28)

No one's going to confuse Hoyer with Aaron Rodgers anytime soon, and the 49ers will be bad in 2017. But that could be a blessing in disguise. Playing while behind means throwing the ball a lot, and garbage time points count the same as any others. From Week 3 to Week 6 last year as the starter in Chicago, Hoyer was 10th in fantasy points among quarterbacks.

Robert Woods, Los Angeles Rams (ADP: WR64)

Sure, Woods is closer in talent level to Charlie Brown than Antonio Brown. And Woods may be about to encounter his own personal Lucy in the form of Jared "One-Hop" Goff. But Woods enters 2017 as the lead receiver for the Rams. And getting any lead receiver this late on draft day has the potential to pay off quite nicely.

21-25

25. David Njoku, Cleveland Browns (ADP: TE21)

It's a rarity for a rookie tight end to make much of a fantasy dent. But the Browns thought well enough of Njoku to let Gary Barnidge go just after selecting the talented youngster from Miami. Njoku will be thrown into the deep end from day one, if only because the Browns don't have a choice. And that'll mean opportunities for fantasy production.

24. Paxton Lynch, Denver Broncos (ADP: QB34)

Mike Klis wrote recently for KUSA-TV in Denver that the "switch was flipped" for Lynch in OTAs—that the second-year quarterback looked much more comfortable running the Broncos offense. This doesn't mean Lynch is a sure bet to beat out Trevor Siemian to start Week 1. But if he does, Lynch has the strong arm and passing-game weapons to put up numbers.

23. Joe Williams, San Francisco 49ers (ADP: RB51)

The San Francisco 49ers moved up in the 2017 NFL draft to select Williams, largely at the behest of head coach Kyle Shanahan. The rookie from Utah ran behind Carlos Hyde at OTAs, but the new regime has no ties to the incumbent back—who's entering a contract year. If Williams wrests the starting job from Hyde (or Hyde gets hurt), it will be late-round jackpot time.

22. Latavius Murray, Minnesota Vikings (ADP: RB36)

Since the Vikings drafted Dalvin Cook in the second round of the 2017 draft, many are ready to hand lead back status to the rookie. Not so fast, according to what Murray told ESPN. "This is my time," Murray said. "This is my opportunity. This is what I want. When it comes Game 1, I need to be back there lining up." Murray has a 1,000-yard season under his belt and rushed for 12 touchdowns last year in Oakland. Reports of his fantasy demise may be exaggerated.

21. Kenny Britt, Cleveland Browns (ADP: WR52)

The Browns brought in Britt in free agency as a replacement for the departed Terrelle Pryor. The Browns' passing game isn't striking fear into any opponents this year, but it's reasonable to expect Britt to get a target load similar to the 111 he saw in 2016. That resulted in 68 catches, just over 1,000 receiving yards and a WR26 finish in fantasy football leagues that award a point for receptions.

16-20

20. Julius Thomas, Miami Dolphins (ADP: TE18)

In Jacksonville, Thomas couldn't come close to the success he had with the Denver Broncos. But Dolphins offensive coordinator Clyde Christensen told ESPN.com's James Walker he thinks Thomas has a ton of potential in his new home. "If Julius Thomas is healthy and we catch some breaks, he can be and has been a 10-touchdown guy," Christensen said. We can hope.

19. Carson Palmer, Arizona Cardinals (ADP: QB21)

Two years ago, Palmer passed for 4,671 yards, tossed 35 touchdowns and finished the season as a top-five fantasy option under center. Last year the yardage and touchdowns were way down, Palmer's interceptions were way up and he barely cracked the top 20. The weapons are there for Palmer in the desert—if the 37-year-old can coax one more year out of his right arm.

18. Eric Decker, Tennessee Titans (ADP: WR42)

This ranking isn't so much about Decker's skill. Provided the 30-year-old is healthy, he's capable of over 1,000 receiving yards and eight to 10 touchdowns as the new No. 1 receiver for the Titans. But the more Decker can demonstrate that his surgically repaired hip and shoulder are good to go, the more the consistently productive veteran's ADP will rise. At this price, though, Decker is highway robbery waiting to happen.

17. Jeremy Maclin, Baltimore Ravens (ADP: WR47)

Just about everything I wrote regarding Decker can be applied to Maclin. He's a veteran with a proven track record who was surprisingly let go by the Kansas City Chiefs after an injury-marred 2016, only to quickly be scooped by a Baltimore Ravens team badly in need of receiver help. But just like Decker, Maclin's price tag will climb now that he's settled in his new home.

16. Kareem Hunt, Kansas City Chiefs (ADP: RB45)

The Chiefs moved up to select Hunt in the third round of the 2017 draft, partly because Spencer Ware faded in a big way over the second half of the 2016 season. Ware is coming off draft boards as a low-end fantasy RB2, but Chiefs beat writer Adam Teicher isn't buying it—he predicted not too long ago at ESPN.com that Hunt will lead the team in both rushing yards and receptions by a tailback in 2017.

15. Blake Bortles, QB, Jacksonville Jaguars

ADP: QB20

There's that dirty look again. The one that says, "Who passed gas in this elevator?"

2017 is a make-or-break season for Jacksonville Jaguars quarterback Blake Bortles. After passing for 4,428 yards and 35 touchdowns in 2015, Bortles regressed big time last season, managing 523 fewer yards, 12 fewer touchdowns and a passer rating nearly 10 points lower than in 2015.

Per John Oehser of the team's website, head coach Doug Marrone said he's liked what he's seen from the 25-year-old in the offseason.

"There are certain things, as far as his elbow and his arm, that are much improved," Marrone said. "I think there are still other things we're still working on as well as everyone else at this stage."

Now, I'm not going to tell you Bortles will repeat his third-place fantasy finish from two seasons ago. That assessment hops the line from optimistic into kooky.

But the Jaguars have a pair of good wide receivers in Allen Hurns and Allen Robinson. They added a talented young back in Leonard Fournette. And the team took steps to get better on the offensive line.

A finish toward the back of the top 10 is reasonable.   

14. C.J. Fiedorowicz, TE, Houston Texans

ADP: TE19

I don't much like C.J. Fiedorowicz personally.

Not because of anything he's done to me, mind you. Or even on the field.

No, it's just because every time I write about him I'm terrified I'll misspell his name—a no-no in my line of work.

Still, if you write about fantasy football you'd better get used to talking about the 25-year-old. Because I expect him to improve on his 2016 performance this year.

In his third NFL season, Fiedorowicz experienced a mini-breakout, hauling in 54 passes for 559 yards and four touchdowns. That ranked him 17th among fantasy tight ends in formats that award a point for receptions.

In other words, even if you think all he'll do is match last year's numbers, Fiedorowicz is still being drafted later in 2017 than his 2016 production indicates he should be.

Whether it's Tom Savage or Deshaun Watson under center for the Texans in 2017, that quarterback will need a safety valve—say a big-bodied 6'5", 265-pounder who has shown the ability to make the tough catch when it counts.

If you're the type of drafter who doesn't like paying retail at tight end and would rather stream a pair of players based on matchups, Fiedorowicz is worth consideration later in drafts.   

13. Rob Kelley, RB, Washington Redskins

ADP: RB39

Most of what I'm about to write could also be said about rookie tailback Samaje Perine (RB41) if he wins the starting job for the Washington Redskins.

Many expect the rookie to do just that, but after showing up to OTAs in excellent shape "Fat Rob" told Nora Princiotti of the Washington Times he welcomes a training camp competition with Perine.

"I think it's best for everybody to have some type of competition going on. Brings the best out of all of us," Kelley said. "I think it's good to have somebody coming in and the offense won't drop off a step."

Kelley's 704 rushing yards on 168 carries (4.2-yard average) isn't jaw-dropping production. But it's worth noting that, per Pro Football Focus, Kelley was third in the NFL among rookie tailbacks last year with 35 missed tackles forced.

However, if you break that down to missed tackles forced per carry, Kelley sails past Dallas' Ezekiel Elliott and Chicago's Jordan Howard to a rookie-leading missed tackle forced every 4.8 carries.

If the D.C. ground game devolves into a full-blown RBBC (running back by committee), Kelley and Perine will see their fantasy ceilings capped.

But if one of these young backs emerges, we'll be looking at a fantasy RB2 available for the cost of an RB4.

12. John Brown, WR, Arizona Cardinals

ADP: WR46

After a 1,000-yard 2015 season, John Brown appeared to be on the rise. But the Arizona Cardinals receiver wasn't himself last year. The blazing speed and explosiveness that made him so dangerous the season before were gone.

As it turns out, the 27-year-old was diagnosed with the sickle-cell trait in October 2016.

The condition is reportedly under control, and as Palmer told Adam Green of Arizona Sports Brown looks like his old speedy self again.

"He doesn't look like he looked like last year," Palmer said. "He just has a different energy about him, he's heavier, he's stronger. He looks more explosive than he did last year.”

In 2015, Brown reeled in 65 catches for 1,003 yards and seven scores—numbers that landed him just inside the top 25 fantasy wideouts in PPR scoring systems.

Yes, his health is a concern. But if he has his condition under control, a finish at or near those 2015 levels is a reasonable expectation—especially in a contract year.

And with Brown's average draft position in low-end fantasy WR4 territory in 12-team leagues, that sets the stage for some big-time value in 2017.

What can Brown do for you?    

11. Doug Martin, RB, Tampa Bay Buccaneers

ADP: RB33

The 2016 season was a rough one for Tampa Bay Buccaneers running back Doug Martin. He played just eight games and gained 421 rushing yards, largely due to a hamstring injury and a late-season suspension for violating the NFL's substance abuse policy, which will carry over to the first three games of 2017. 

However, after Martin's stint in rehab, Tampa general manager Jason Licht told the NFL Network's Mike Garafolo (via colleague Kevin Patra) that Martin looked reborn in OTAs.

"I had a conversation with [Licht]," Garafolo said. "[Martin] looks lean, he looks like he's finishing his runs—obviously, there is no contact in the spring—but it looks like he's finishing his runs. He looks like he's got that burst. He looks like the Doug Martin of 2015."

That Martin of 2015 finished second in the NFL with 1,402 rushing yards and ranked fourth among running backs in PPR fantasy points.

As Mike Florio pointed out at Pro Football Talk, there's no guarantee Martin will even have a job when he returns at the end of September. The team doesn't owe Martin any guaranteed money thanks to the suspension, and head coach Dirk Koetter has made zero guarantees about Martin's spot on the team.

There's risk involved with drafting Martin. But the potential reward of a fantasy RB1 for the cost of an RB3 is tempting.

Especially since rookie Jeremy McNichols and/or Jacquizz Rodgers can be added late as insurance.

10. Tyrell Williams, WR, Los Angeles Chargers

ADP: WR45

Last year, in his second season, Tyrell Williams came from nowhere to lead the Chargers with 1,059 receiving yards. He scored seven touchdowns and was the second-most productive wide receiver in the NFL from the slot, according to PFF, trailing only Jordy Nelson.

Williams finished 18th in PPR fantasy points among wide receivers. And yet, he’s being drafted well outside the top 40 at his position.

Yes, the Chargers drafted Clemson’s Mike Williams at No. 7 overall. But Williams has seen his acclimation to the NFL grind to a halt thanks to a back injury. He missed most of OTAs, and his status for the beginning of training camp is unclear.

Yes, the Chargers get Keenan Allen back in 2017, but for how long? Allen is a star when on the field, but he missed almost the entire 2016 season and 23 of his last 32 games.

Even if both are on the field in Week 1, Williams will at least live up to his low-end fantasy WR4 price tag. He’s not going to go from 120 targets to 20. If (when) either of them misses time, Williams will shatter it.

9. Quincy Enunwa, WR, New York Jets

ADP: WR58

It wasn’t to the extent of Tyrell Williams, but Quincy Enunwa had a breakout of his own for the Jets in 2016, reeling in 58 passes for 857 yards and four scores.

There’s a good chance Enunwa will improve those numbers in 2017—if only because he’s the last man standing for Gang Green at wide receiver.

After the Jets parted ways with both Brandon Marshall and Eric Decker in the offseason, Enunwa is now the nominal No. 1 wideout. He told Darryl Slater of NJ.com he’s on board both with that new role and new coordinator John Morton’s offense.

"I love it so far," Enunwa said. "I think it's a good opportunity for guys to get the ball and make plays. It's also a great opportunity for us to not get as many turnovers. It's really predicated to getting the ball out fast. There are many audibles to create quick throws. I think everybody is kind of buying in."

The Jets are going to be an awful football team in 2017, but Enunwa has WR3 upside based on opportunity alone—and a fantasy ceiling quite a bit higher.

8. Paul Perkins, RB, New York Giants

ADP: RB32

The Giants raised eyebrows this spring when they made little effort to upgrade a backfield that was among the worst in 2016.

However, Giants running backs coach Craig Johnson told Jordan Raanan of ESPN he’s confident that second-year pro Paul Perkins can take the reins as the lead back for Big Blue.

"I really like what Paul Perkins has been doing so far," Johnson said. "He ended last season playing like a guy that is ready to take over the job. There is nothing so far in the offseason to show he’s not going to be able to handle that role."

Perkins was hardly a world-beater as a rookie, rushing for 456 yards and averaging 4.1 yards a carry. But that average was a full half-yard better than any other tailback on the roster, and Perkins improved as the season wore on—including a 21-carry, 102-yard effort against Washington in the regular-season finale.

The Giants have a veteran third-down back in Shane Vereen, and the team added a power back in Clemson’s Wayne Gallman on Day 3 of the draft.

But the door is wide-open for Perkins, and lead backs aren’t usually available this late on draft day.

7. Jack Doyle, TE, Indianapolis Colts

ADP: TE13

The tight end position is a crapshoot this year. There are a handful of reliable starters at the top of the rankings, and then a whole lot of maybe.

Smart fantasy owners should consider Jack Doyle, who was rewarded with a $19 million contract extension after a career year in 2016. Doyle told Kevin Bowen of the team’s website he knows the increased paycheck brings expectations.

"Just trying to be more of a leader in the tight end room and on the offensive side of the ball is something I’m trying to do and get better at," Doyle said. "I’ve had to lead before. I didn’t feel like it was necessarily with my role early in my career but definitely now. I’m trying to do more things to improve in that area and help the team."

Doyle posted 59 catches for 584 yards and five scores in 2016, production that landed him 13th among tight ends in PPR leagues.

But Doyle is now the unquestioned No. 1 tight end for a quarterback in Andrew Luck who has been known to lean on the position in the past. A small boost in production, and Doyle is a decent weekly fantasy starter.

6. Marvin Jones, WR, Detroit Lions

ADP: WR51

Over the first three weeks of the 2016 season, Marvin Jones had 408 receiving yards and two touchdowns. He was the highest-scoring wide receiver in PPR leagues. Over the first half of the year, he was a top-10 fantasy option at his position.

Jones spent the second half of the campaign on a milk carton, though.

Determined to avoid that second-half swoon in 2017, Jones spent part of the offseason working out with Randy Moss. Lions head coach Jim Caldwell told Nate Atkins of MLive.com he’s noticed a difference in the 27-year-old this summer.

"He's had one of those springs that you kind of look to," Caldwell said. "This guy is right there on the verge of maintaining that explosive start that he had last year."

Jones can’t be expected to maintain that torrid pace, but he still has WR1 upside as a WR5.

5. Philip Rivers, QB, Los Angeles Chargers

ADP: QB15

In 2016, Philip Rivers had, by his standards, a down season. His 60.4 completion percentage was his lowest in more than a decade. He tossed a career-high 21 interceptions. His passer rating was under 90 for the first time since 2012.

However, the 35-year-old insisted to ESPN he’s in no hurry to ride off into the sunset.

"I don't want to hang on at the end and just be a guy that's hanging on," Rivers said. "But if I still feel like I can help a team and I enjoy it the way I do and more importantly, if the team feels that I can help them. ... I don't see myself shutting it down any time real soon."

Even in that "down" year, Rivers topped 4,300 passing yards, threw 33 touchdown passes and finished eighth in fantasy points among quarterbacks—all with an injury-ravaged receiving corps and offensive line.

That offensive line is improved in 2017. So is the receiving corps with the addition of No. 7 overall pick Mike Williams and the return of Keenan Allen. Rivers also has a talented young tailback at his disposal in Melvin Gordon.

He will finish inside the top 10, and he could hit the top five if things break right.

4. Danny Woodhead, RB, Baltimore Ravens

ADP: RB30

Danny Woodhead is a 32-year-old scatback who has missed at least 13 games in two of the last three seasons—including 14 in 2016 with a torn ACL.

That’s the bad news.

Woodhead is also an annually underrated PPR machine who is fitting right in at Baltimore.

That’s the good news.

Quarterback Joe Flacco told Ryan Mink of the team's website that it’s great to have a safety valve out of the backfield again.

"Really, ever since we lost Ray Rice, we haven’t had a type of back that’s quite like how Ray was and quite like how Danny is in the passing game," Flacco said. "They just have a very good feel for when they’re open and how to get open, how to sit in holes, how to find my eyes and you can already see that. You can see he has a really good feel for those kinds of things."

From 2009 to 2013, Rice averaged 67 catches a year. In Woodhead’s last full season (2015), he topped 80 grabs for the Chargers.

That season, Woodhead ranked third in fantasy points at running back in leagues that award a point for catches. Seventy catches and a top-15 PPR finish are within the veteran’s reach.

3. Matthew Stafford, QB, Detroit Lions

ADP: QB14

Matthew Stafford is the oldest 29-year-old in the NFL; it seems like he's been playing quarterback for the Lions forever.

Stafford’s eighth campaign was typical. He completed over 65 percent of his passes for over 4,300 yards, finishing the year with a passer rating over 90 and the seventh-most fantasy points among quarterbacks in NFL.com's default scoring.

Had Stafford’s touchdown total not been relatively low (24), he would have cracked the top five.

Stafford is also entering a contract year (again), but he told ESPN’s Michael Rothstein he isn’t worried about talk that he’s set to become the highest-paid player in the NFL.

"I'm just worried about trying to get better out here," Stafford said. "That's pretty much all I can say. This time of year, to me, is football time."

Uh-huh. Sure. After all, $100 million is so, you know, whatever.

Stafford has every reason to play well this season, and he has the weapons at his disposal to thrive. He’s one of the poster children for why it’s smart to wait at quarterback when drafting.

2. Frank Gore, RB, Indianapolis Colts

ADP: RB37

News flash: Frank Gore is old. He turned 34 in May, which is 119 in running back years.

Gore didn’t play old in 2016, though. Yes, he averaged under four yards a carry. But he also became the first Colts tailback in a decade to top 1,000 yards on the ground. He also topped that same benchmark in total yards for the 11th time—in a row.

Gore told Mike Wells of ESPN he has every intention of going for an even dozen.

"I feel as long as I’m healthy and my guys up front and I get the opportunities, I’m going to be successful," Gore said. "I think the more I’m successful, the more this team will be successful. I don’t really think about yards and that anymore, but like I said, as long as I’m playing healthy, that’ll come."

I get that Gore is at the age where "the edge" could come at any time. It’s remarkable that it hasn’t already. We haven’t seen a player this age have this much success running the ball since Hall of Famer Curtis Martin.

But Gore's lowest fantasy finish in PPR leagues since 2005 was 21st (in 2014). Last year he was a fantasy RB1 in 12-team leagues.

For what he’s costing in drafts, I’ll roll the dice that he has one more year left.

1. Pierre Garcon, WR, San Francisco 49ers

ADP: WR41

Last year, Pierre Garcon snared 79 passes for 1,041 yards and three touchdowns with the Redskins. He ranked inside the top 25 receivers in PPR formats.

This year, the 30-year-old is getting the Rodney Dangerfield treatment in fantasy drafts. Call it "the San Francisco effect."

I’m not going to tell you the Brian Hoyer-led 49ers are going to be an offensive juggernaut. That would be, um, yeah. But Garcon is the unquestioned lead receiver and primary target in a Kyle Shanahan offense. He's a veteran who the 49ers felt strongly enough about to make a substantial financial commitment (around $16 million) in 2016.

Garcon knows Shanahan’s scheme from their time together in D.C. And per Pro Football Focus, Garcon has the third-lowest drop rate of any receiver over the last two years.

We have a sure-handed receiver with a track record of producing who will be far and away the most targeted pass-catcher in a Shanahan offense for a team that will be playing from behind a lot.

In his current draft slot (as a mid-range WR4 in 12-team leagues), Garcon is absolute larceny. I’d love to get him as a WR3 in leagues where I target the running back position early.

It wouldn’t surprise me if he backs up last year’s WR22 finish, and I wouldn’t be floored if he sneaks into the back end of the top 20.

Fantasy rankings courtesy of MyFantasyLeague.com, FFToday and Football Diehards, unless otherwise noted.