All Major League Baseball prospects who are hot at any given moment are precious commodities.

For contenders, they're also expendable.

We're going to look at 10 prospects whom teams should be prepared to sell high on in the upcoming trade season. These are players who either came into 2018 with high stock or who have already dramatically boosted their stock with their performances. Either way, they serve their parent clubs better as trade chips than as potential reinforcements.

We'll go team by team in alphabetical order by city.

Boston Red Sox: Jalen Beeks

The Boston Red Sox's farm system isn't deep these days, and Jalen Beeks wasn't even regarded as one of its best players coming into the year.

But, man, does he look good early on.

Beeks owns a 1.71 ERA over 26.1 innings through five starts for Triple-A Pawtucket. The left-hander has walked only seven batters and leads the International League with 46 strikeouts. 

What sets the 24-year-old apart is a diverse repertoire of pitches that now features a cutter that he learned from watching Jon Lester and David Price.

"He took it upon himself to study the best in the game, and evaluate video, and trying to find a different solution as far as making the ball move," Pawtucket manager Kevin Boles told WEEI.com's Alex Reimer. "He's found something. This pitch has the chance to be a quality major league pitch."

But at 5'11", 195 pounds, Beeks is an undersized pitching prospect. There also isn't a need for him in the Red Sox's major league starting rotation. So rather than risk watching his value tumble back to earth, they're better off trying to use him as the centerpiece in a trade for an upgrade at catcher or in their bullpen.

Cleveland Indians: Shane Bieber

Shane Bieber (who's not pictured because no pictures of him are readily available) isn't the best pitching prospect in baseball. But he might be the one who's most ready for The Show right now.

The garden-variety pitching prospect is a thrower first and a pitcher second. Bieber is the opposite. The 22-year-old gets a 70 grade for his control from MLB.com, and it shows in how he's walked only 0.6 batters per nine innings in three minor league seasons.

The right-hander also boasts a 2.35 ERA and strong marks in strikeouts (8.3 K/9) and home runs allowed (0.4 HR/9). He's also coming off a 2017 campaign in which he led the minors with 173.1 innings.

Because Bieber was recently promoted to Triple-A Columbus and the Cleveland Indians are getting zilch out of Josh Tomlin, it's possible to see a near future in which Bieber steps into the big club's rotation and stays there.

What this Indians team needs, however, is not a savior on the mound. It has a much bigger need for offense, as they rank seventh in the American League in runs scored and 12th in OPS.

The trade market is their best avenue for fixing that, and trading Bieber is much more palatable than dealing Francisco Mejia or Triston McKenzie.

Houston Astros: Yordan Alvarez

Everyone is anxiously awaiting the arrival of uber-prospect Kyle Tucker, but he's not the hottest of the Houston Astros' top prospects.

That would be Yordan Alvarez.

Alvarez got a dose of humility after he was moved from Single-A to High-A in 2017, as his OPS dropped from 1.125 to .722. But the Astros bumped him up to Double-A Corpus Christi for the start of 2018 anyway, and he's rewarding their confidence with a .916 OPS and six long balls through 27 games.

As nice as the power is, even more encouraging is how Alvarez has tightened his approach and bumped his walk rate from 7.5 percent at High-A up to 11.4 percent.

"He's getting better at plate discipline," Corpus Christi manager Omar Lopez said. "When the ball's in the zone, he'll make contact or foul it off. When there are mistakes, that's when he can really do damage."

The catch is that Alvarez's arrival in Houston is likely far from imminent. He's only 20 years old, and the Astros have enough offense to avoid rushing him to the majors.

Of course, they're also very much a win-now team. Among other things, it behooves such teams to have better closers than Ken Giles. Alvarez could be just the ticket for the Astros to find an upgrade on the trade market.

Los Angeles Angels: Jo Adell

The Los Angeles Angels' best prospect is technically still Shohei Ohtani. But as soon as Ohtani's prospect status runs out, the honor will pass to Jo Adell.

The outfielder was the Angels' No. 10 pick in the 2017 draft, and he immediately made good on the hype with a .908 OPS in 49 games at Rookie ball. He then opened 2018 as a consensus top-100 prospect.

A thumb injury slowed down the Adell hype train for a while but he's still managed a .907 OPS in 14 games for Single-A Burlington. His strikeout rate (31.7 K%) is a concern, but it's offset by his strong approach (11.7 BB%) and his built-in combination of power and speed.

Angels fans shouldn't hold their breath for Adell, though. Between his 19 years of age and his current station in the minors, he's not likely to arrive in the majors until 2020 or maybe even 2021.

That means Adell is more so an heir apparent to Mike Trout than a future partner in crime. The Angels' immediate priority is, of course, making the most out of Trout's time with the team. The current season is presenting a golden opportunity to do so, and it'll become even more golden if Adell is traded for a much-needed rotation asset.

Los Angeles Dodgers: Yusniel Diaz

The effort to win 104 regular-season games and traverse to Game 7 of the World Series in 2017 appears to be taking a toll on the Los Angeles Dodgers in 2018. They've been wrecked by injuries in a slow start.

It's still highly unlikely that the Dodgers will fall out of the race and thus highly likely that they'll try to use the trade market to fix what ails them. The trick will be to do so without sacrificing Walker Buehler or Alex Verdugo, whose time to help the Dodgers has come.

As an alternative, they'll have to consider Yusniel Diaz.

The 21-year-old outfielder came into the year as one of Los Angeles' better prospect, and now he's threatening to become its best. Despite an injury that's limited him to 15 games, he's put up a 1.004 OPS for Triple-A Tulsa. He's making huge strides with his approach, going from a 45-to-102 walk-to-strikeout ratio in 2017 to an 11-to-10 mark early in 2018.

Due to his youth an relative inexperience, however, the only way Diaz is going to help the Dodgers this season is by netting them a much-needed player in a trade. With Corey Seager out for the year, they especially need help at shortstop.

Milwaukee Brewers: Brett Phillips

Yes, Brett Phillips is still technically a prospect despite serving various stints with the Milwaukee Brewers. And yes, he's still an interesting prospect.

The 23-year-old has always had an intriguing defensive profile thanks to his speed and inhuman arm strength. It's his hitting ability that's typically been at the center of questions about his upside. 

Phillips pushed back against the questions with a .305 average and .944 OPS in 105 games for Triple-A Colorado Springs in 2017. That's where he's spent most of his 2018 season thus far. And while his OPS has dropped to .888, it's a good look that he's collected nearly as many walks (16) as strikeouts (23).

No matter what Phillips does, however, it's going to be tough for him to gain a foothold in a Brewers outfield that's being held down by Christian Yelich, Lorenzo Cain and Domingo Santana. He'll also have Ryan Braun standing in his way once Eric Thames gets healthy.

Milwaukee is presently using Phillips as a reserve outfielder. That's fine for the moment, but such a role may only diminish his trade value. Rather than risk that, the Brewers should attempt to use him as a centerpiece in a deal for a top-level starting pitcher.

New York Yankees: Jonathan Loaisiga

The New York Yankees are already reveling in the excellence of rookie infielders Gleyber Torres and Miguel Andujar. It's just a matter of time before they call on prized lefty Justus Sheffield next.

Another guy who looks like he wants to join the party is Jonathan Loaisiga.

The fact that the 23-year-old is still pitching is a feat in its own right. He was signed by the San Francisco Giants in 2012, but they let him go after he missed 2014 and 2015 with injuries.

Loaisiga caught on with the Yankees in 2016 and re-established his stock with a 1.83 ERA in 15 starts in 2017. Now he finds himself with a 1.44 ERA through five starts between High-A and Double-A, with 10 times as many strikeouts (30) as walks (3) in 25 innings. At work there is strong command of an arsenal based around a mid-90s fastball.

But at 5'11" and 165 pounds, Loaisiga is smaller than a typical starting pitcher. That could force him into relief work in the long run. As it is, he is unlikely to get to the majors before 2019.

Because the Yankees are set on winning their 28th World Series title this season, Loaisiga's surging stock is most useful to them on the trade market, where they could seek a first baseman or a bullpen arm.

San Francisco Giants: Chris Shaw

Chris Shaw fits best with a team on which he can play first base. 

In other words: not the San Francisco Giants. 

The Giants have Brandon Belt signed through 2021, and they have little reason to move him off first base any time soon. He hits enough for the position and is quietly one of the better defenders there, too.

Of course, Shaw was an outfielder when the Giants drafted him at No. 31 overall in 2015. And he moved back to the outfield on a full-time basis in 2017.

Alas, his poor speed makes him strictly a corner outfielder—and one who fits best at ballparks with short porches. AT&T Park doesn't fit the bill, and the Giants need to reserve their corners for Andrew McCutchen, Mac Williamson and, when healthy, Hunter Pence anyway.

What Shaw does have going for him is an all-powerful bat. He slugged 24 homers in 125 games at Double-A and Triple-A in 2017, and he's already up to nine homers through 29 games for Triple-A Sacramento this season. Power like that is useful for downplaying his ugly 6-to-47 walk-to-strikeout ratio.

In all, Shaw is just the guy for the Giants to trade in a deal for much-needed pitching help.

Toronto Blue Jays: Kevin Smith

With Josh Donaldson due for free agency at season's end, the Toronto Blue Jays have a lot riding on the 2018 season. And while they're good, they must be better if they want to keep up with Boston and New York.

Better trade Kevin Smith.

The Blue Jays took Smith (another guy whose picture isn't readily available) in the fourth round of the 2017 draft. He was well-regarded for his defense and power potential at the time, but there were concerns about whether his swing-and-miss tendency would derail his development.

Smith, 21, is quickly putting those concerns to rest in his first full professional season. He's struck out only 18 times in 30 games with Single-A Lansing. He hasn't had to sacrifice any production for the extra contact, as he's managed a 1.055 OPS and clubbed four homers.

Nonetheless, Smith is probably still two or three years away from debuting with Toronto. And by the time he's ready, he could be trying to crack an infield with Bo Bichette and Logan Warmoth on either side of second base and Vladimir Guerrero Jr. at third base.

Rather than leave him to that fate, the Blue Jays should try to trade Smith for somebody who could help fix their rotation's 5.49 ERA.

Washington Nationals: Juan Soto

It's understandable if the Washington Nationals' first instinct with Juan Soto is to tell other teams to back the hell off.

The outfielder has already become so much more than the well-regarded prospect that he was coming into 2018. He started with a 1.300 OPS and five homers in 16 games for Single-A Hagerstown. He then got bumped to High-A Potomac, for whom he's put up a 1.275 OPS and six homers in only 14 games.

By the way, this dude is still only 19 years old.

At the least, Soto has leap-frogged Victor Robles as the most exciting prospect in Washington's farm system. At most, he's put himself in the running for the best prospect in baseball.

But while the Nationals could wait for Soto, it could mean waiting until 2020. He's not going to help them this year, which is kinda-sorta-definitely an important year for the franchise with Bryce Harper (and others) due for free agency.

At this rate, Soto could be used to land just about any trade candidate. With needs at catcher, in the outfield and in their bullpen, the Nationals have plenty of excuses to cash him in.

Stats courtesy of Baseball Reference, FanGraphs and MiLB.com.