With each passing game, the line between being a buyer at the MLB July 31 non-waiver trade deadline and being a seller is becoming more defined.

Clubs like the Miami Marlins, for example, are on the verge of having to make a harsh decision. Namely, do they build for the future by pulling the cord on this season, or do they go all in and risk getting nothing in return for players who have legitimate trade value?

Other teams have players under contract for the next season or two but would be wise to consider moving a star performer for a number of prospects.

As such, we will take a look at five MLBers whose names aren’t generally bandied about in trade rumors but could be in the coming weeks.

Truth be told, very few players are completely untouchable—even on contending teams—so this list will be pointed. That is to say that only players whose names are rarely mentioned, yet aren’t out of reality's realm, will be included.

Here are the five MLB names that could soon be on the 2014 MLB trade block.

Steve Cishek, CL, Miami Marlins

The Miami Marlins enjoyed a fantastic start to the season, going 34-30 over the first 64 games, and they were tied for first place in the National League East as late as June 8. Since then, however, they have gone 10-16 and sat 5.0 games behind the Washington Nationals when play began on Wednesday.

If they continue to fall in the standings, closer Steve Cishek is one of the players on the 25-man roster who could find himself on the trading block.

In fact, this idea was introduced by Peter Gammons about a month ago. Gammons wrote:

Bambi is a huge part of the Marlins’ improvement, 15-for-16 in saves, a 2.36 earned run average, throws strikes, reliable person. But if Miami falls back in July, he could be a big chip for one of the many teams—like the Tigers—who have struggled at the end of games. He’s the Marlins third highest-paid player at $3.8M, and arbitration is going to drive that way up. The Marlins have been trying to assemble backend arms, and right now have closer possibilities in Bryan Morris and Anthony DeSclafani—if not Nathan Eovaldi—and could get some young infield offensive help in return.

Now at the time Gammons wrote that, the Marlins were in the middle of a fight for first place, meaning the likelihood that Cishek would be dealt was quite low. Well, the club's fortunes have changed, but Cishek is still performing at a high level.

Entering play on Wednesday, he was 4-4 with a 3.05 ERA, 2.05 FIP, 1.096 WHIP and averaged 10.6 strikeouts per nine innings. He also had a .216 batting average against, and he'd only blown two saves in 22 opportunities (per splits taken from Baseball-Reference.com).

That stat line should be very attractive to several teams, including the Detroit Tigers, San Francisco Giants and Oakland A’s. That he isn’t scheduled to hit free agency until after the 2017 season is also appealing to a team looking to acquire a closer. Combine his production with team control, and the return for his services could be quite good.

All told, Cishek is one of the better closers in the National League. Is he in the same conversation as Craig Kimbrel or Huston Street? No, but they are exceptional at what they do.

As the July 31 non-waiver trade deadline approaches, expect for Cishek to not only hit the trade market in full force, but to garner quite a bit of interest.

Casey McGehee, 3B, Miami Marlins

Like closer Steve Cishek, third baseman Casey McGehee is another member of the Miami Marlins who, if the club doesn’t improve in the standings, could find himself shopped as the July 31 non-waiver trade deadline nears.

To be sure, Marlins general manager Dan Jennings is saying the right things. While deflecting rumors about Giancarlo Stanton, for example, USA Today’s Bob Nightengale quoted Jennings saying that McGehee “ain’t going nowhere, either.”

Now that could be posturing, but the larger point is that it sounds like other teams are already asking about the 31-year-old, who is only earning $1.1 million this season and is arbitration eligible for one more season.

From a production standpoint, McGehee’s numbers are fairly impressive. He has a .318/.386/.390 slash line with 110 hits, 20 doubles, and 53 RBI, and he's drawn 41 walks in 346 at-bats. Defensively, he is holding his own, but his true value is at the plate.

Those raw numbers are a bit misleading, however.

Consider that he has a .368 batting average on balls in play (BAbip), which is untenable, and with men on base his BAbip goes up to .409, and with runners in scoring position it jumps to .451. However it’s sliced, the success is unlikely to continue. And let’s not forget that he only had a .072 ISO going into action on Wednesday.

Do other general managers know about the thin edge McGehee is walking on? Of course they do. If the Marlins end up selling, however, quite a few of them would be willing to part with a couple of prospects for his services.

Another thing to keep in mind regarding McGehee’s overall value is that in addition to third base, he can play first, has served as the designated hitter during interleague play and could likely play in the outfield if needed. In other words, he is versatile.

Jon Lester, SP, Boston Red Sox

For all of the talk regarding contract extensions and negotiations being put on hold until after the season, Boston Red Sox general manager Ben Cherington may just end up trading Jon Lester for a bundle of prospects.

Make no mistake: The Red Sox are in a world of hurt right now. Losers of 13 of their last 18 games going into Wednesday's tilt with the Chicago White Sox, the club looks lost in almost every phase. True, they are getting relatively decent pitching, but the roster just isn’t capable of competing on a nightly basis.

On top of the poor play on the field, there is confusion regarding Lester’s situation. During an appearance on Boston’s WEEI, ESPN.com’s Buster Olney provided some insight:

At some point recently, the Red Sox … have been trying to get this thing, at least to get to a point where they’re putting an offer on the table, but I think the horse is out the barn door … I think it’s all but over that Jon Lester is going into free agency and I think the only way that they circumvent that is if the Red Sox do what the Phillies did two years ago with Cole Hamels and say, ‘OK, sorry about that. We’re totally wrong and we’re willing to give you a top-of-the-market deal for [$140 million-$150 million],’ and I think there’s no chance of that happening.

The larger idea that Olney was getting at is that the stalled negotiations mean Lester will head into the offseason as a free agent after finishing the year with the Red Sox. If things keep going the way they are, that would be a mistake.

See, two things would happen if they traded their No. 1 starter. As Tyler Drenon from SB Nation's MLB Daily Dish opined, "they could injure the [Tampa Bay] Rays leverage [sic] in trade talks for [left-hander David] Price.” In essence, Cherington would handcuff the Rays by putting his ace on the market at the same time they do.

They would also be able to target some help in the outfield and infield. That would help the club immensely as each is an area of concern moving forward. In other words, why use minor league pitching to acquire a player at each position when Lester may be enough to address them both?

Either way, it looks like Lester is on his way out. He will no doubt be offered an enormous contract this offseason that the Red Sox may or may not be able to match. Moving him in advance of the July 31 non-waiver trade deadline makes sense, especially since there are so many talented pitchers at Double-A and Triple-A.

Lester is 9-7 with a 2.73 ERA and 122 strikeouts in 122.0 innings pitched this season.

Adrian Beltre, 3B, Texas Rangers

Texas Rangers third baseman Adrian Beltre is the best offensive third baseman in baseball.

Going into action on Wednesday, he had a .333/.379/.533 slash line with 12 home runs, 48 RBI and 20 doubles. On top of those statistics, Beltre is putting up a .933 OPS with runners on base and a .994 OPS with runners in scoring position, according to splits taken from Baseball-Reference.

He has been sensational.

He could also find his way onto the trading block.

Now one thing standing in the way of moving Beltre is his contract. Not only is he owed $18 million next season, but he has a $16 million option for the 2016 season based upon plate appearances that is sure to vest at his current rate.

That gives Rangers general manager Jon Daniels two options. He could send cash over in any deal to increase the quality of prospects he gets in return, or he could try to swing a trade that relieves him of the financial burden of Beltre’s contract but limits the talent he gets back.

Either way, Beltre is a fantastic trade piece who will garner quite a bit of interest.

Another thing to consider is that it appears Joey Gallo is ready to take the reins whenever they are handed to him. In 83 games between Single-A and Double-A, he is slashing at .314/.441/.721 with 31 home runs and 73 RBI in 83 games. Even more impressive, he has 10 home runs in only 94 at-bats since his promotion to Frisco.

To be sure, Daniels is already doing his due diligence. Evan Grant from the Dallas Morning News noted that Daniels “has started doing what any GM in his shoes would do” by “checking to see what some ‘core-type’ players might bring in a trade.”

Don’t’ be surprised if Beltre takes the leap from being a general topic of discussion to a player who is actively shopped in the coming weeks.

Justin Masterson, SP, Cleveland Indians

How quickly times have changed.

Not long ago, the Cleveland Indians were vilified by some for taking a hard line with starting pitcher Justin Masterson's contract. Now, he is on the 15-day disabled list with knee inflammation after starting the season 4-6 with a 5.51 ERA and a 1.653 WHIP. He has also walked 56 batters in 98.0 innings pitched.

Truthfully, Masterson has largely hurt the Indians more than he has helped them.

Now one could argue that given his poor performance this season, he would generate little trade interest. That belief is off the mark. Given his past success, there are a number of teams that would gladly bring him over as they make a push toward the postseason.

Yes, the return will be minimal, but he still has value nonetheless. All he may need is a mechanical adjustment or a change of scenery to once again be a force in any rotation.

Another reason Masterson will likely end up on the trading block regards his contract. As it stands, the Indians have two choices if he is still on the roster once the season ends.

First, they can make him a qualifying offer as a Type A free agent. If he refuses, they would get a compensatory draft pick in return. The problem there is that he will probably accept the offer in hope of rebounding next year and getting a larger contract during the 2015 offseason.

The other option is to let him walk outright. Simply put, neither of those choices are very attractive for general manager Chris Antonetti. He needs to put Masterson on the block and get whatever he can in return.

None of this means that the Indians are going to begin selling off multiple assets and give up on the 2014 season. They are very much in the thick of the playoff picture. Assuming Masterson’s knee does not require surgery, moving him is smart business.

One final thing to consider is that Antonetti could add a different starting pitcher via trade or call up Danny Salazar from Triple-A Columbus to take his place.

Unless otherwise noted, all general, split and advanced statistics are courtesy of Baseball-Reference and are accurate as of game time on Wednesday, July 9. Transaction, injury, prospect and game information are courtesy of MLB.com. Contract information was taken from Cot’s Contracts.

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