MLB Prospect Debuts: Fantasy Baseball Waiver Wire Pickups and Rookie Stashes (Week 13)

Mike's fantasy baseball prospect stashes, sleepers, and rookie waiver wire pickups for Week 13 of 2025 -- recent MLB prospect debuts and potential call-ups to monitor.

Summer is here as June comes to a close next week, and it's time to look for some waiver wire pickups and rookie stashes that could help you in the coming second half of the fantasy baseball season.

Remember, there is no secret knowledge of who is getting the call and when; this is all speculation on who is playing well and could get an opportunity based on need, whether that need is an injury to a star player, or an ineffective player, or a fellow young guy in need of an IL stint to rest and recuperate from the rigors of a long season.

These players offer intriguing upside for the fantasy manager willing to show patience with rostering a young player, as opposed to rostering a boring veteran who may not help your team at all. Let's take a look at a few players who intrigue fantasy players.

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Fantasy Baseball Hitter Prospects To Target

Samuel Basallo, C, Baltimore Orioles

Level: Triple-A

2025 Stats: 196 PA, .271/.378/.590, 33 R, 15 HR, 34 RBI, 0 SB, 14.3% BB%, 23.5% K%, 152 wRC+

The oblique injury to Adley Rutschman will likely keep him out until after the All-Star break, leaving the Orioles to rotate Gary Sanchez and Chadwick Tromp (for the concussed Maverick Handley). This could create a temptation to recall the 20-year-old Basallo, the top prospect in a loaded Baltimore system.

Basallo has nothing to prove with the bat; he is hitting .271 with 15 home runs this season. The issue that holds Basallo back is his defense, which is a work in progress behind the plate; he has a strong arm but is reportedly in need of improvement in his receiving.

Injuries have slowed his development as a catcher, with elbow issues being the predominant issue. There appears to be some chase in his game, but the power is a legitimate 80-grade tool with development. It will be interesting to see if the Orioles are tempted to recall him due to their current catching woes. Stay tuned.

You can see that Basallo has put together an excellent June in the box below, hitting a whopping .352 with six home runs and 14 RBI.

Chase DeLauter, OF, Cleveland Guardians

Level: Triple-A

2025 Stats: 119 PA, .271/.403/.479, 17 R, 5 HR, 17 RBI, 1 SB, 18.5% BB%, 13.4% K%, 138 wRC+

The Guardians have struggled all season to find productive outfield play, and DeLauter is showing signs in Triple-A that he could be ready for his major league debut. What's interesting about DeLauter is that he walks more (18.5%) than he strikes out (13.4%), and he puts the ball in play.

He doesn't have one standout skill that catches the eye to make you see him as a category stuffer, but that may be hard to determine yet, as foot and ankle injuries have wreaked havoc on his early career. He had sports hernia surgery in March and just recently joined the Triple-A team at Columbus.

DeLauter is one to monitor because the hit tool is such that it could cause the Guardians to call him up sooner rather than later. He looks to be a corner outfielder. DeLauter's biggest issue appears to be staying on the field and being available to play.

Colby Thomas, OF, Athletics

Level: Triple-A

2025 Stats: 330 PA, .297/.362./548, 58 R, 17 HR, 66 RBI, 6 SB, 6.7% BB%, 26.1% K%, 113 wRC+ 

Thomas is relatively unknown outside those who follow prospects very closely, but his chance could be coming for the Athletics. The team has shown a recent propensity for giving young players an opportunity at the major league level, such as Denzel Clarke and Jacob Wilson.

Thomas could be next. He has a mix of power and speed, with 17 home runs and six stolen bases this season. Thomas is coming off a 2024 season in which he slugged 31 home runs while also stealing 15 bases. The issue is swing and miss; last season, he struck out over 30% of the time in Triple-A, while this season, he has shaved that down to 26.1%.

He is a corner outfielder who may be able to hit for power if he gets the promotion. Not a widely known prospect, if Thomas keeps hitting, expect a promotion this summer.

Fantasy Baseball Pitcher Prospects To Target

Joe Boyle, Tampa Bay Rays 

Level: Triple-A 

2025 Stats: 64 IP, 1.83 ERA, 0.95 WHIP, 32.3% K%, 10% BB%, 3.51 FIP

Boyle is playing his trade in Triple-A right now, but many pundits feel it is just a matter of time until the Rays recall him.  The numbers are eye-catching, with a 1.83 ERA, a 0.95 WHIP, and a 32.3% K%, which is outstanding.

He made one start for the big league club and pitched well, earning a win over five innings while garnering seven strikeouts. For his efforts, he was returned to Triple-A. It seems like Boyle is the next man up should anyone in the current rotation lose their spot due to injury or ineffectiveness.

Boyle features a three-pitch mix, using his four-seamer the most at 53%, a slider at 30%, and a split-finger fastball at 18%. His velocity tops out at about 98 MPH, which puts him above the league average. The right-hander was acquired from the Athletics last winter and, given the opportunity, could do well in the major leagues.

Chase Burns, Cincinnati Reds

Level: Called Up

2025 Stats: 66 IP, 1.77 ERA, 0.77 WHIP, 36.8% K%, 5.4% BB%, 2.13 FIP

The baseball world waits in excitement as Burns was recalled over the weekend and will make his first start against the New York Yankees. His next starts line up to be against Boston and Philadelphia, so management did him no favors with these matchups.

Yet, it will be exciting to see how he fares in his debut. There is nothing left to prove in the minor leagues; see his box below and look for yourself. Seven wins in 13 starts, with a 1.77 ERA, a 0.77 WHIP, and a whopping 36.8% K% that show he has been getting it done.

The velocity is elite, but the command has been an issue in the past, which seems to be behind him now, but could rear its head at any time. Look for Burns to be a middle-of-the-rotation guy for the near future, with the potential to become an ace in a couple of years.

Carson Whisenhunt, San Francisco Giants 

Level: Triple-A 

2025 Stats: 79 IP, 4.10 ERA, 1.19 WHIP, 22% K%, 5.6% BB%, 4.43 FIP

It's interesting to talk about Whisenhunt and compare him to the higher-octane guys like Boyle and Burns mentioned above. Why? Because, as the top pitching prospect for the San Francisco Giants, his best pitch is a changeup, which has an elite 80-grade.

You'll note the ERA is higher than one would like, the strikeout percentage middling, the walk percentage quite good. Whisenhunt moved from a mediocre curveball to a serviceable slider in the last two seasons. With two starters with checkered injury histories in Justin Verlander and Robbie Ray, and the possibility that Landen Roupp could get some time to rest this summer, Whisenhunt should be on your radar.

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