3 Impact Fantasy Baseball Prospects To Stash - Coby Mayo, Quinn Mathews, Andrew Painter

Joey analyzes three top fantasy baseball prospects - Coby Mayo, Quinn Mathews, Andrew Painter - who could make big impacts this season. These MLB prospects are potential waiver wire pick-ups or stashes.

There are always prospects who get called up throughout the season and make an immediate impact in the pros. It happens every year. In 2024, Paul Skenes, James Wood, and Rhett Lowder didn't start the year with the major league club, but all three players were fantastic fantasy stashes. If you especially held on to the first two names, there's a good chance they helped you in the fantasy playoffs.

Skenes had a 1.96 ERA in his 23 starts, Wood had nine home runs, 41 RBI, and 14 stolen bases over the final three months, and Lowder gave up just four runs across 30 2/3 innings in his six starts at the end of the year. That means fantasy managers should be stashing at least one prospect on their roster at this point in the season.

Three potential prospect stashes to consider are Coby Mayo, Quinn Mathews, and Andrew Painter. All three players are widely available and should be called up at some point in 2025.  So, let's dive in and see if Mayo, Mathews, and Painter should be stashed and grabbed off the waiver wire before it's too late.

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Coby Mayo, 3B, Baltimore Orioles

Current Level: Triple-A Norfolk
Availability: 7% rostered
2024 MLB stats: 17 G, .098/.196/.098, 4 H, 4 R, 4 BB, 22 SO

The Baltimore Orioles had high hopes for Mayo during the 2024 season after the third baseman tore it up in the minors the previous three years. He hit .319 with nine home runs in his first taste of minor league ball back in 2021 and then put up unbelievable numbers in a full season at Double-A and Triple-A in 2023.

The slugger hit a combined .290 with 29 home runs, 45 doubles, 99 RBI, and five stolen bases.

Although Mayo began the 2024 campaign in the minors, his strong numbers in the first four months earned him a promotion to the major league club at the beginning of August. However, the third baseman looked overmatched at the plate with the Orioles. He had just four hits across 41 at-bats (.098 batting average) with 22 strikeouts and no extra-base hits.

I've seen Coby Mayo's rough 41 MLB ABs being conflated with a disappointing 2024, but it really was another good season from him as a 22-year-old in Triple-A.

93 G: .293/.372/.592, 25 HR, 25 K%, 145 wRC+

155 career AAA games: .283/.380/.562, 37 HR, 138 wRC+

— Aram Leighton (@AramLeighton8) March 18, 2025

There's no doubt that Mayo struggled in his first go-around in the majors, and those struggles even continued into the spring. MLB Pipeline's No. 13 overall prospect batted just .190 with three doubles and three RBI across 46 plate appearances during spring training. As a result, he isn't a stash candidate at this point in the 2025 season.

The 23-year-old is hitting only .196 with one home run and 15 strikeouts in his first 12 games at Triple-A Norfolk, making it hard to stash him in all formats. While the potential and power are both there for Mayo, he didn't show any of that in his first 17 games with the Orioles last season. Therefore, fantasy managers should only be watching him on the waiver wire for now.

Quinn Mathews, SP, St. Louis Cardinals

Current Level: Triple-A Memphis
Availability: 7% rostered
2024 AA stats: 9 GS, 2.41 ERA, 70 SO, 52 1/3 IP, 0.96 WHIP
2024 AAA stats: 4 GS, 6.48 ERA, 22 SO, 16 2/3 IP, 1.92 WHIP

Mathews has quickly risen up the minor league ranks since being drafted in the fourth round of the 2023 MLB Draft. The left-hander finished with a combined 2.76 ERA, a 0.98 WHIP, and 202 strikeouts across 143 1/3 innings pitched at Single-A, High-A, Double-A, and Triple-A last season. That strong campaign now puts him as the 45th-best prospect in baseball, according to MLB Pipeline.

However, it wasn't all great for Mathews in his first minor league season. The southpaw had a tough time adjusting to the Triple-A level, allowing 12 earned runs across 16 2/3 innings pitched (6.48 ERA). Opposing hitters also had a whopping .281 batting average and 18 hits against him in his four starts with the Redbirds.

Even though Mathews has done a better job in his first two Triple-A starts this season, command has been a real issue for him in the early going. He walked three batters in four innings in his first outing on March 29 and issued six more walks in three 2/3 innings on April 4. The good news is that the 24-year-old gave up only three runs in those two appearances.

Quinn Mathews' changeup recorded a ridiculous 52% whiff rate last year.

Here he gets one of the best hitters in the sport to chase his bread-and-butter. pic.twitter.com/nzPTb2uRRj

— Kareem (@KareemSSN) February 25, 2025

If Mathews can have better command on the mound over the next few weeks, there's a chance we will see him in St. Louis sooner rather than later. The Cardinals' pitching staff has struggled to begin the season, and the left-hander could eventually take Matthew Liberatore's spot in the rotation. Liberatore has given up eight runs across 12 1/3 innings of work (5.84 ERA) so far this year.

As a result, Mathews could be a potential stash in deeper leagues or NL-only formats. He has shown his potential in the minors, and both his fastball and changeup are plus pitches for him. With the southpaw expected to make his debut at some point in 2025, he's worth hanging onto in some cases.

Andrew Painter, SP, Philadelphia Phillies

Level: Single-A Clearwater
Availability: 15% rostered
2022 MiLB stats: 22 GS, 1.56 ERA, 155 SO, 103 2/3 IP, 0.89 WHIP

It has been a while since the Philadelphia Phillies have seen their top prospect pitch in the minors. Painter initially injured his elbow during spring training in 2023 but didn't undergo Tommy John surgery until the end of July that same year. That resulted in the right-hander missing the entire 2023 and 2024 seasons.

Before his injury, though, Painter was unstoppable in the minors. He allowed zero runs in his four starts at rookie ball in 2021 and then finished with a combined 1.56 ERA and 155 strikeouts in 22 starts at Single-A, High-A, and Double-A. In those 22 appearances, the former 13th overall pick in the 2021 MLB Draft held opposing hitters to a .181 batting average.

Although Painter is still recovering from that elbow injury, he is making significant progress toward a return. The 22-year-old is scheduled to make his first minor league start since 2022 on Friday, April 11, at Single-A Clearwater. Given how long he has been out, the Phillies will likely be extremely cautious with their prized pitcher.

Therefore, it will likely be some time until we see Painter make his Phillies debut. He needs to build up his pitch count, and the right-hander has yet to throw in Triple-A in his minor league career. However, he is definitely worth waiting for, making him a strong fantasy stash in most 12-plus team leagues.

Rob Thomson said Andrew Painter will begin his climb through the minors on Friday. He will start in Low-A Clearwater and pitch a couple of innings. pic.twitter.com/QpQchAj3vc

— Devan Kaney (@Devan_Kaney) April 6, 2025

Painter will soon be the best pitching prospect in baseball, once Jackson Jobe officially hits the 50-inning threshold, and we saw his potential back in the Arizona Fall League this past October. The flame-throwing right-hander allowed just four runs across 15 2/3 innings pitched (2.30 ERA) in six starts.

That's why Painter is currently one of the best prospect stashes for fantasy managers. He has a mean fastball that can touch 96 mph, and it's only a matter of time until we see the 22-year-old up with the Phillies. It might not be until the second half of the season, but he can certainly make an immediate impact in the majors once he is promoted.

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