We spend a lot of time talking about a team's top prospects, but what about the next prospect?

Sometimes those are one and the same, like in the case of Toronto Blue Jays phenom Vladimir Guerrero Jr., who is already pounding down the door for a promotion.

Other times, it's a largely unheralded middle reliever or a second-tier position player who winds up providing in-house support.

Ahead we've taken a closer look at the one prospect from each team who is ready to help in the majors.

Players were chosen based on a combination of their individual development and production as well as their path to MLB playing time, based on current or expected team needs.

Arizona Diamondbacks: RHP Jon Duplantier

Jon Duplantier has already received a taste of big league action this season when he was promoted briefly to add some length to a taxed bullpen.

He threw three scoreless innings and recorded a save in his MLB debut on April 1 and made one more appearance before he returned to Triple-A where he'll continue to work as a starter.

The 24-year-old has a 1.77 ERA, 1.04 WHIP and 249 strikeouts in 214 career minor league innings since being selected in the third round of the 2016 draft, so there's little left for him to prove in the minors.

Expect Duplantier to lock down a rotation spot before 2019 is over.

Atlanta Braves: LHP Kolby Allard

Left-hander Kolby Allard is off to the best start of any of the Atlanta Braves' bumper crop of quality pitching prospects.

The 21-year-old has allowed just seven hits and one earned run in 9.1 innings over his first two starts at Triple-A Gwinnett, walking two and striking out eight.

He's more of a high-floor guy than a high-ceiling potential future ace, and that's caused his stock to slip a bit over the past year. With a polished three-pitch mix and solid command, he's still more than capable of holding down a spot at the back of the rotation for a long time.

Baltimore Orioles: LF DJ Stewart

The No. 25 pick in the 2015 draft, DJ Stewart continues to show the intriguing on-base skills that could ultimately be his ticket to an MLB role.

The 25-year-old hit a middling .235 with 24 doubles and 12 home runs at Triple-A last season but managed a .329 on-base percentage thanks to an 11.0 percent walk rate.

In parts of five minor league seasons, he has a .352 on-base percentage and a 12.4 percent walk rate, and he's shown enough pop to be a 20-homer guy in the majors.

He's limited to left field defensively, which narrows his path to the big leagues. If he keeps getting on base, the Orioles will find a spot for him.

Boston Red Sox: LHP Darwinzon Hernandez

Already one of the most promising young arms in the Boston Red Sox system, Darwinzon Hernandez turned heads during the Arizona Fall League when he posted a 1.59 ERA with 24 strikeouts in 11.1 innings.

The 22-year-old continued to impress this spring with a 0.82 ERA and 12 strikeouts in 11 innings of work before he was optioned to Double-A.

For all the positives, his command remains a work in progress. MLB.com wrote, "If he can't make it as a starter, he definitely has the stuff to project as a potential closer."

Regardless of his role, with the Red Sox struggling to an MLB-worst 6.09 ERA this season, he should be able to help in some capacity.

Chicago Cubs: RHP Dakota Mekkes

The Chicago Cubs bullpen has struggled in the early going, pitching to a 5.43 ERA with three losses and three blown saves.

With a lot of moving parts in the relief corps this season, Dakota Mekkes is almost guaranteed to make his MLB debut in 2019 after he was sent to Triple-A to start the year.

A 10th-round pick in 2016, Mekkes has compiled a 1.19 ERA, 1.06 WHIP and 11.3 K/9 in 151.2 career innings while climbing the minor league ladder.

A deceptive delivery helps his 92-93 mph fastball play up, and he backs it with an average slider/changeup combination, giving him the requisite tools to make an impact as a middle reliever.

Chicago White Sox: RHP Dylan Cease

With Eloy Jimenez already on the MLB roster and Michael Kopech sidelined for the season while he recovers from Tommy John surgery, a strong case can be made that Dylan Cease is the top prospect in the Chicago White Sox system.

And yes, that includes Luis Robert, who is off to a torrid start at High-A.

Cease, 23, can approach triple digits with his fastball, and his hammer curve is one of the best off-speed pitches in the minors. He rounds out his repertoire with a slider and changeup that both flash above average.

The stuff has always been there, it's the command that's the question. He trimmed his walk rate from 4.2 to 3.6 BB/9 last year, and he's issued just one free pass in 10 innings of work this year. It's looking more and more like he'll deliver on his potential as a top-of-the-rotation starter.

Cincinnati Reds: RHP Jimmy Herget

At 25 years old, Jimmy Herget is on the edge of the prospect scale.

The right-handed reliever has drawn comparisons to Steve Cishek for his sidewinder delivery and fastball/slider approach.

He's struck out nine without allowing an earned run in six innings of work this season at Triple-A, and he's now logged 98 innings at the level.

There are still some questions about his command, but he's ready to help a Cincinnati Reds bullpen that has been a bit shaky to start the year with six losses and three blown saves.

Cleveland Indians: OF Oscar Mercado

Oscar Mercado hit .400/.415/.750 with three doubles, one triple and three home runs in 41 plate appearances this spring while trying to win a spot in the Cleveland Indians outfield.

The 24-year-old was ultimately sent to Triple-A, where he's 10-for-39 with three doubles while sporting a .383 on-base percentage to begin the year.

If the Carlos Gonzalez experiment fails, he could be next in line for a corner outfield spot. One way or another, he should get a chance to show what he can do at the MLB level before the 2019 season comes to a close.

Colorado Rockies: 2B/SS Brendan Rodgers

The second base position has produced a .171/.227/.257 line for the Colorado Rockies this season.

Daniel Murphy and Ryan McMahon are both on the injured list, while rookie Garrett Hampson is hitting .200/.224/.309 with 16 strikeouts in 59 plate appearances.

It might only be a matter of time before Brendan Rodgers gets his chance.

The No. 3 pick in the 2015 draft and the consensus top prospect in the Colorado system has hit every step of the way, and he's off to a solid start at Triple-A. His 60-grade hit tool and 55-grade power could be just what the Rockies need to spark a sputtering offense.

Detroit Tigers: CF Daz Cameron

Daz Cameron was one of the standout prospects of the spring, hitting .357/.438/.786 with seven extra-base hits in 32 plate appearances before he was sent to Triple-A.

The 22-year-old has come a long way since hitting .212/.287/.321 with a 33.5 percent strikeout rate during his full-season debut in 2016.

There's still a good deal of swing-and-miss to his game and likely always will be, but he's improved his approach to better tap into his impressive raw tools.

Don't be surprised if he's the everyday center fielder in Detroit before the 2019 season is over.

Houston Astros: 1B/OF Yordan Alvarez

All due respect to Forrest Whitley and Kyle Tucker, who are two of the top prospects in all of baseball, but Yordan Alvarez has looked like the most MLB-ready player in the Houston Astros system.

The imposing 6'5", 225-pound slugger is hitting .300/.451/.875 with seven home runs and 17 RBI in his first 12 games at Triple-A Round Rock, and he's logged more walks (10) than strikeouts (9).

The 21-year-old has seen his stock trend steadily upward since he made his pro debut in 2016, and he hit .293/.369/.534 with 21 doubles, 20 home runs and 74 RBI in 88 games between Double-A and Triple-A last year.

He's ready.

Kansas City Royals: RHP Josh Staumont

Few prospects throw harder than Josh Staumont.

Now that the Kansas City Royals have finally committed to using him as a reliever, rather than trying to get him to rein his stuff in while working as a starter, he could move quickly.

The 25-year-old struck out 103 batters in 74.1 innings last season at Triple-A, but he also walked 52 hitters for a 6.3 BB/9 walk rate that was still an improvement over his 7.1 BB/9 career rate.

At some point, the Royals are going to want a closer look. If everything clicks, he could be closing games in the not-too-distant future.

Los Angeles Angels: RHP Griffin Canning

After slipping to the second round of the 2017 draft, Griffin Canning immediately established himself as the top pitching prospect in the Los Angeles Angels system in his pro debut.

The 22-year-old posted a 3.65 ERA, 1.26 WHIP and 125 strikeouts in 113.1 innings while climbing two levels to reach Triple-A.

After getting knocked around a bit at the highest level of the minors last season, he's started off strong this year with a 0.90 ERA, 1.10 WHIP and 11 strikeouts in 10 innings.

With a polished repertoire that features four above-average pitches and plus command, he could be the ace of the Angels' staff by 2020.

Los Angeles Dodgers: RHP Mitchell White

If the Los Angeles Dodgers decide to use Mitchell White as a reliever, he could make a major impact this season.

The 24-year-old is currently working as a starter at Double-A Tulsa, where he's recorded nine strikeouts over seven scoreless innings. But if you'll recall, Walker Buehler made his MLB debut as a reliever to help out a thin bullpen before eventually settling into a starting role.

MLB.com wrote of White: "He has the upside of a mid-rotation starter who can generate more than his share of swings-and-misses as well as ground-ball contact. He also could be a high-leverage reliever who could concentrate on attacking hitters with his fastball and breaking balls."

A promotion to Triple-A and a short-term move to a relief role could be forthcoming.

Miami Marlins: RHP Zac Gallen

The Miami Marlins currently rank 17th in the majors with a 4.62 starters' ERA, and the starting staff has gone 3-9 on the year.

Meanwhile, right-hander Zac Gallen has allowed just three hits in 13 innings of work over his first two starts at Triple-A, walking none and striking out 19 for a sterling 0.23 WHIP.

That's next-level dominant, and it should earn him a promotion to the majors in short order.

The 23-year-old "gets results without plus stuff," as MLB.com put it, and he has one of the highest floors of any upper-level pitching prospect.

It's time to see what he can do.

Milwaukee Brewers: RHP Adrian Houser

Despite struggling to a 5.03 ERA and 1.54 WHIP in 78.2 innings as a starter in the minors last season, Adrian Houser pitched fairly well in a relief role in the majors with a 3.29 ERA in 13.2 innings over seven appearances.

Back at Triple-A and back to starting, he's posted a 1.10 ERA and 0.74 WHIP with an 18-to-2 strikeout-to-walk ratio in 16.1 innings this season.

Whether the Milwaukee Brewers call him up to fill a spot in the rotation or slot him in the bullpen as a multi-inning weapon, it looks like he's ready for another shot at the big leagues.

Minnesota Twins: RHP Griffin Jax

This was a tricky one.

The Minnesota Twins' top position-player prospects are still a ways away from the majors, and starting pitcher Brusdar Graterol might be capable of getting MLB hitters out, but calling him up now would be rushing him.

Digging a bit deeper, one pitching prospect who could be on the fast track is Griffin Jax, due in part to his advanced age. Drafted in the third round of the 2016 draft out of Air Force, Jax is finally able to turn his full attention to baseball after being granted a deferment as part of the World Class Athlete Program.

He's already 24, and with 10.2 scoreless innings under his belt already at Double-A, it might not be long before he gets the call to Triple-A.

Jax throws a lot of strikes and gets a lot of ground balls, and there's always a place for someone like that on the MLB staff in some capacity.

New York Mets: LHP Daniel Zamora

With Luis Avilan struggling to a 10.80 ERA while allowing 13 hits and three walks in 6.2 innings, it might not be long before the New York Mets are exploring alternative options to be the second lefty in the bullpen alongside Justin Wilson.

One option will be Daniel Zamora.

The 26-year-old made 18 appearances at the MLB level last season, posting a 3.00 ERA with 16 strikeouts in nine innings of work.

MLB.com wrote: "Zamora is largely a one-pitch reliever, throwing his slider about 79 percent of the time from a nearly sidearm slot. The extreme usage speaks to the pitch's effectiveness, as its high spin rate and hard downer action nets Zamora whiffs on both sides of the plate."

That one standout pitch is enough to make him a better option than Avilan at this point.

New York Yankees: RHP Domingo Acevedo

The most MLB-ready prospect in the New York Yankees system is right-hander Jonathan Loaisiga.

He's already made two starts for the big league club this season, and he has 31.2 innings at the MLB level to his credit. That said, keeping him stretched out as a starter in Triple-A makes sense, so we'll go a different route with the Yankees pick.

Hard-throwing Domingo Acevedo has been used primarily as a starter to this point in his career. The 25-year-old has made the full-time move to the bullpen this season, though, and could move quickly as a result.

MLB.com wrote, "His inability to stay healthy makes it less realistic he'll survive as a starter, though he could be an intriguing bullpen option who could throw harder in shorter stints."

Once clocked as high as 103 mph before dialing it back to the mid-90s as a starter, the towering 6'7" right-hander could enjoy a Dellin Betances-type ascent now that he's pitching in shorter stints.

Oakland Athletics: C Sean Murphy

Left-hander Jesus Luzardo is as close to MLB-ready as any pitching prospect in baseball. However, he's been sidelined by a left shoulder strain to start the year and will have some work to do building up his arm once he returns to action.

So instead, we'll go with catcher Sean Murphy as the prospect most ready to help the Oakland Athletics.

Always known as a plus defender with a rocket arm, Murphy enjoyed a breakout offensive season at Double-A last year before his season was cut short by a broken right hamate bone.

The 24-year-old has returned with a flourish in Triple-A, hitting .405/.500/.568 in his first 10 games while throwing out two of six attempted base-stealers.

Once Murphy is deemed ready, Josh Phegley and Nick Hundley are not going to stand in his way, even with Phegley off to an unexpectedly hot start.

Philadelphia Phillies: RHP Enyel De Los Santos

The Philadelphia Phillies picked up Enyel De Los Santos in the deal that sent Freddy Galvis to the San Diego Padres prior to last season.

The 23-year-old went 10-5 with a 2.63 ERA, 1.16 WHIP and 110 strikeouts in 126.2 innings at Triple-A last season, and he got his first taste of MLB action with two starts and five relief appearances spanning 19 innings.

Whether he steps into the rotation as a fill-in when injury strikes or finds himself in a multi-inning role out of the bullpen, he's ready to contribute at the big league level.

The development of his curveball will ultimately determine whether he can stick as a starter.

Pittsburgh Pirates: OF Bryan Reynolds

The Pittsburgh Pirates have a number of top prospects on the cusp of MLB action.

Third baseman Ke'Bryan Hayes, shortstop Cole Tucker and right-hander Mitch Keller should all carve out MLB jobs before the end of the 2019 season.

However, in terms of who is next, keep an eye on outfielder Bryan Reynolds.

The former San Francisco Giants prospect who was acquired in the Andrew McCutchen trade is hitting .349/.417/.698 with four home runs in his first 11 games at Triple-A this year.

It remains to be seen if he'll hit for power at the MLB level, but the hit tool is legitimate, and his ability to play all three outfield spots further adds to his value.

San Diego Padres: RHP Cal Quantrill

Cal Quantrill saw his stock drop a bit last season when he posted a 4.80 ERA and 1.47 WHIP over 148 innings between Double-A and Triple-A.

However, he's still a polished arm with a high floor and tantalizing upside.

MLB.com wrote, "His impressive blend of size, stuff and pitchability make him a candidate to join the Padres' rotation at some point midseason."

The 24-year-old was shelled in his first start of the year at Triple-A, allowing nine hits and eight runs (six earned) over three innings. He's looked sharp in his two starts since, though, and is putting himself in position to be the next man up in the San Diego rotation.

San Francisco Giants: RHP Tyler Beede

While the luster has faded from his prospect star, Tyler Beede is still capable of being a long-term piece of the puzzle for the rebuilding San Francisco Giants.

The 25-year-old suffered through a disastrous 2018 season, serving up a 6.64 ERA and 1.78 WHIP in 80 minor league innings, and allowing nine hits and seven earned runs in 7.2 innings at the MLB level.

Beede has the stuff and the durable frame to succeed as a big league starter. It's his spotty command that has kept him from reaching his full potential, as he walked 59 batters at a 6.6 BB/9 clip last season.

He's off to a strong start at Triple-A with a 2.84 ERA and 22 strikeouts in 12.2 innings, though he's still struggling to limit walks with seven for a 5.0 BB/9 rate.

Seattle Mariners: OF Braden Bishop

The Seattle Mariners are set in the outfield with Domingo Santana, Mallex Smith and Mitch Haniger in the starting lineup and Jay Bruce also capable of making the occasional start in right field.

However, should injury strike, Braden Bishop is ready.

The 25-year-old is hitting .333/.435/.462 with five doubles in nine games at Triple-A Tacoma, and he was part of the expanded roster for the season-opening series in Japan with the Oakland Athletics.

A career .295/.368/.387 hitter in the minors, Bishop posted a .379/.419/.724 line with three home runs in 31 plate appearances during spring training.

With plus speed and the ability to play all three outfield spots, he profiles great as a fourth outfielder with the potential for more.

St. Louis Cardinals: C Andrew Knizner

Until Yadier Molina retires, he'll be the starting catcher for the St. Louis Cardinals.

However, it might behoove them to give the 36-year-old more frequent rest to keep him fresh and productive.

While Matt Wieters is an acceptable veteran stopgap, Andrew Knizner represents the position's future, and he's close to MLB-ready.

The 24-year-old is hitting .303 with a .395 on-base percentage at Triple-A to start the 2019 season, and he's hit every step of the way since St. Louis selected him in the seventh round of the 2016 draft.

Learning alongside Molina in the majors might be more beneficial than further minor league seasoning.

Tampa Bay Rays: 1B Nate Lowe

Nate Lowe was one of the most productive hitters in minor league baseball last season.

The 23-year-old batted .330/.416/.568 with 32 doubles, 27 home runs and 102 RBI over three levels, closing out the year with 28 games at Triple-A.

With a 55-grade hit tool backing his tremendous raw power, he has a chance to be a prototypical middle-of-the-order slugger for a Tampa Bay Rays team that seems to always be looking for an offensive spark.

Ji-Man Choi has a .690 OPS with zero home runs in 63 plate appearances as the everyday first baseman to start the year. If he doesn't pick it up soon, Lowe will get the call before the All-Star break.

Texas Rangers: LHP Taylor Hearn

The Texas Rangers snagged left-hander Taylor Hearn in the deal that sent reliever Keone Kela to the Pittsburgh Pirates last summer.

The 6'5" lefty can dial his fastball up to triple digits, and he backs it with a solid changeup that can be a real weapon when he has a feel for it.

The development of his curveball as a passable third offering has his long-term role in question.

The 24-year-old is off to a strong start at Triple-A with a 3.86 ERA and 20 strikeouts in 14 innings. He's reached an age when he'll need to either prove he can stick as a starter or move to the bullpen—where his power stuff would play immediately.

Regardless of his role, expect to see him in the majors this summer.

Toronto Blue Jays: 3B Vladimir Guerrero Jr.

Do we really need to go over this again?

When you hit .381/.437/.636 with 50 extra-base hits in 95 games and reach Triple-A before your 20th birthday, there's nothing more to be gained from playing in the minors.

That is, of course, for team control.

Toronto Blue Jays prospect Vladimir Guerrero Jr. will immediately be one of the best pure hitters in baseball the second he steps into a major league batter's box for the first time.

He's a future superstar and a generational talent. Enough said.

Washington Nationals: SS Carter Kieboom

Incumbent shortstop Trea Turner's broken finger could open the door for Carter Kieboom to receive an early promotion from the Washington Nationals.

A similar situation put Juan Soto in the majors last year sooner than expected, and that worked out pretty well, as he put up a .923 OPS in 116 games.

Kieboom, 21, is a career .283/.368/.468 hitter with a 60-grade hit tool and 55-grade power.

While he may end up at second base, he's capable of handling shortstop, and with a .381/.490/.667 line and seven extra-base hits in 11 games at Triple-A, he's making a strong case for a call-up.

All stats courtesy of Baseball Reference and FanGraphs, unless otherwise noted, and accurate through April 16.