10 Relief Pitcher Prospects To Know For 2024 Fantasy Baseball
Image credit: Michael Mercado (Photo by Scott Audette/MLB Photos via Getty Images)
Projecting relief pitchers is a thankless task, let alone relief-pitching prospects. However, for those of us who devote countless hours researching and preparing for fantasy baseball, it can be a crucial task. For leagues that don’t allow in-season transactions, betting on a relief pitcher without a clearly defined role would be ill advised. However, in leagues where you can pick players up, knowing which relievers might be “for real” and which relievers are just flukes can be the difference between winning and losing.
Today, we’re going to dive deep on 10 names you should keep your eyes on. If these guys get a chance due to injury, or the incumbent closer losing effectiveness, they may be worth targeting.
Michael Mercado, RHP, Phillies
Sometimes we forget how long athletes can toil in the minor leagues chasing a dream they’ve worked toward their entire lives. Mercado was drafted No. 40 overall by the Rays in 2017 after ranking as the No. 48 prospect in the 2017 draft. He was later traded to the Phillies for Adam Leverett and is currently our No. 33 prospect in their org.
Now, Mercado looks like a potential relief ace. His fastball provides an excellent base. It’s a high-velocity, high-ride pitch that will dominate at the top of the zone. This spring, Mercado is averaging 17.8 inches of induced vertical break (rise) on his fastball at 96.6 mph, about 1.9 inches more rise than a typical pitcher will get from a similar arm slot after adjusting for velocity (faster pitches have less time to rise). He’s lowered his arm slot a little compared to last year, but the pitch is still getting a lot of ride, which should help the fastball play up a tiny bit more. It’s a present MLB quality pitch, if he can land it for strikes.
Mercado throws a pitch that is classified as a cutter, but it’s very similar in shape to a gyro slider (a pitch that is mostly gravity and seam-shifted wake movement). It performed exceptionally well last year and was the pitch he was able to throw for strikes. Sliders are typically great pitches when thrown as hard as Mercado throws his cutter, meaning there may be some more potential for this pitch if he makes it into a true gyro slider, though it remains a potentially plus pitch as is and should play at least average with the current shape. We have him as throwing both a slider and a cutter in the minors, though the shapes are very similar.
The curveball might be the best swing-and-miss pitch in Mercado’s arsenal, at least by results, garnering a 60% whiff rate in the minors last season, though he struggled to throw it for strikes.
A three-pitch mix, headlined by a plus fastball, with two distinct breaking balls? Sounds like a guy who can pitch in high-leverage situations.
Zach Maxwell, RHP, Reds
Maxwell is a big boy, listed at 6-foot-6, 275 pounds, and ranks as the Reds’ No. 28 Prospect entering 2024 while earning comparisons to Jonathan Broxton.
Here’s what he looks like from behind the plate:
His fastball averaged 98.4 in the Arizona Fall League with an excellent 18.3 inches of induced vertical break (18.9 inches when normalized for pitch speed), which is almost three inches more ride than a typical pitcher will get from that arm slot. That’s exceptional, and supports his absurd 34% in-zone whiff rate with the pitch. Even with his current spotty command, the pitch will be a dominant force, with elite upside.
He complements his fastball with a hard bullet slider with great depth at 87-89 mph, both good indicators of a plus slider. As Eno Sarris loves to say, it’s very hard to have a bad slider if you’re throwing it 89 mph. This is an absolutely monstrous profile that could be a top-end closer if he gets even a small uptick in command. He’ll likely start the season at Double-A, and could be a dominant stretch away from a big league callup, though he may need another season before he’s ready for the big show.
Franco Aleman, RHP, Guardians
Over his last 27 innings across Double-A and spring training, Aleman has a 0.00 ERA (yes, that’s not a typo) with 44 strikeouts, good for a K% north of 42%. Aleman is a massive dude, listed at 6-foot-6 and 235 pounds, and he looks like a closer.
The four-seam fastball doesn’t get insane ride, but he has a low three-quarters slot, which helps the ride play up. It’s a two-plane (i.e. lots of horizontal and vertical movement) 96-97 mph fastball that Double-A batters chased up and out of the zone with regularity. He also throws a two-seam fastball, which is a good pitch, but not as good as the four-seam.
He rounds out his arsenal with a bullet slider around 84-85 mph that garnered a phenomenal 41% CSW and 20% SwStr%, along with a 44.5% whiff rate. This is entirely subjective, but he looks like he has the mound presence of an elite closer, and I think he could be the next closer for the Guardians when they inevitably trade away Clase.
Prelander Berroa, RHP, White Sox
Berroa is the rare relief-pitcher prospect with a long history of Top 30 Prospects rankings, currently our No. 10 prospect for the White Sox, after ranking 11th for Seattle in 2023 and No. 29 for San Francisco in ‘2022. He’s a modern-day Carlos Marmol, with outlandish stuff, but very little command.
For Berroa, everything starts with the slider, which he throws more than his fastball. It’s a plus-plus bullet slider that he just can’t command, grading out as a 127 Stuff+, as per Eno Sarris, in its short sample in the majors. The slider absolutely carved up Double-A hitters, to the tune of a 53.5% whiff rate, along with a 33% chase rate, and they couldn’t do much damage against it, even when they did make contact. He may be better served upping his usage of the pitch, following the Andres Munoz template.
His fastball is no slouch either, though it may only be an average major league fastball at his current velocity. He was closer to 97 in the minors, and lost about a half tick in his brief callup, with only about one inch more ride than expected given the release point. If he can start sitting closer to his max of 100, both the fastball and slider could be lethal. Our report has him with the potential for a 70-grade fastball and 70-grade slider, but presently as his current velo I’d give him a 60-grade fastball and 70-grade slider.
If the fastball velo ticks back up, and he ups his usage of the slider, Berroa could be closing games for the White Sox so long as the next guy on this list doesn’t beat him out for the job.
Jordan Leasure, RHP, White Sox
Surprise! We have another pitcher with a strong fastball/slider pair. Jordan Leasure ranked as our No. 15 prospect for the White Sox on the strength of his 70-grade fastball and plus slider.
In Triple-A, Leasure’s fastball averaged 97.2 mph with 18.1 inches of induced vertical break, which is good on its own, but outstanding given his release point, as he gets over three inches more ride than expected. Across the minor leagues last year, the four-seam fastball had a strong 19.2 SwStr%, and he managed to throw enough strikes.
Leasure’s slider isn’t far off from some elite sliders from a shape and velocity standpoint, but he doesn’t get the elite results you’d expect. My take is that he may be a tweak away from unlocking the slider and becoming the no-doubt closer for the White Sox. Between Jordan and Prelander, the White Sox could have a lethal duo at the back of their pens, but if I had to guess which one will end up closing, I’d probably go with Leasure.
John McMillon, RHP, Royals
You guessed it, another dominant fastball/slider closer type, saving perhaps the best pure stuff for last. We have MLB Statcast data for McMillon, so we can have a tiny bit more confidence in him, and understand why he struck out 99 batters in 55 innings across four levels.
While in Double-A, McMillon averaged almost 19 inches of IVB, but sat closer to 16 inches in his 21-pitch MLB sample, so while the movement profile was pretty average, he did it while averaging 98.8 mph and topping out at 100.5 mph.
It’s unclear if his fastball shape changed from the minors to the majors, but we’ll know for sure when we get a larger sample of pitches this season. What is consistent from the minors to the majors is the variance in his release point. His fastball is released almost four inches closer to his body than his slider, which might explain why it didn’t perform as well, as MLB hitters would be more capable of picking up on it.
The money pitch is the slider, which is a true bullet/gyro slider at 87 mph. It was only a 32-pitch MLB sample, but it clocked a massive 37.5% SwStr%, which is only slightly higher than his minor league 31.2% SwStr%.
Tyler Mattison, RHP, Tigers
Okay, I get it, you want to read about a pitcher with a deeper arsenal. Enter Tyler Mattison, our No. 24 prospect for the Tigers, who profiles as a potential four-pitch James Karinchak. He has Karinchak’s fastball metrics (release point, ride, extension, velocity) with perhaps slightly better command. That’s an excellent base to start from. It’s an outlier release point, which is usually a good thing when it comes to pitchers.
His primary secondary is a hard curveball at 83 mph (some might call it a slurve) that generated a phenomenal 51% whiff rate, and was tremendous at limiting damage when batters where able to get their bat on it. He also throws a gyro slider with negative IVB at 84 mph (distinct shape from the slurve), which was good for a 40% whiff rate, better chase rates than the curve and also limited damage on contact. Both of these pitches can be plus pitches.
He rounds out his arsenal with a changeup that’s had success in the lower minors, though that doesn’t always translate smoothly to the bigs. He probably only needs it against lefties, and it provides him with a pitch that has a decent amount of horizontal movement.
Overall, it’s a very north-south operation for Mattison, which is a recipe for a lot of swings and misses. Mattison took a massive leap forward in 2024, and could be a short burst of Triple-A dominance away from finding his way to the back of Detroit’s bullpen.
Alex Hoppe, RHP, Red Sox
You could say that he has some “Hoppe” on his fastball, averaging 98 mph on the pitch while topping out at 99.5 mph, but it gets most of its value from the velocity, as the ride is closer to solid-average even given the lower slot. He fills the zone with the pitch, but it doesn’t project to be a pitch that he can dominate major league hitters with.
The slider might be an elite bat-misser, generating a 50% whiff rate and a 35% chase rate at a firm 87 mph. It has great depth and some run, moving in the opposite direction to the fastball, but he struggles to throw it for strikes. He has also flashed a promising changeup, with good fade and depth, and about 10 mph separation from the fastball. He’s primarily used it as a chase pitch, but it has potential as a weapon against lefties.
It’s likely that his slider is better than his fastball, but the command is holding back how much he can use it. If he figures it out and flips the usage (more sliders than fastballs) he might be the eighth-inning guy in Boston late this season.
Bryce Montes de Oca, RHP, Mets
Montes de Oca generated a lot of hype last spring training with his elite sinker, averaging 99.2 mph with 17 inches of run, and he’s been measured as high as 102.4 mph. We’ve seen pitchers with elite velo sinkers become dominant closers, such as Blake Treinen and Brusdar Graterol. Montes de Oca gets almost seven feet of extension on the pitch, helping the elite velo play up.
He throws both a hard cutter around 95 and an occasional 86 mph slider. The cutter likely has more potential, but just needs to be a solid-average pitch, as he’ll want to throw that sinker most of the time. If Montes de Oca returns healthy from his Tommy John surgery, he could join Edwin Diaz as a dynamic duo in Gotham City.
Kyle Hurt, RHP, Dodgers
We wrote about Hurt as one of our Bold Predictions.
Bonus: Michel Otanez – Oakland Athletics
I’ll be very brief with Otanez. In spring training 2022, Otanez featured a four-seam fastball at 99 mph with 18.6 inches of IVB; elite fastball metrics that would play in the big leagues. At some point after that, he changed his mechanics, lowered his arm slot and lost all the carry on his fastball, as well as what semblance of command he had. If (and this is a gigantic if) he can re-create what he had in the spring of 2022, this is a potentially elite bullpen arm with just the fastball. The early spring results have been very poor, so this is not a name to keep an eye on right now, but a spot for this writer to lament what could have been.
