5 Relievers to Put on Your Radar
Justin Slaten, Kyle Leahy, Ryan Zeferjahn, Yimi García, Shelby Miller
With the 2025 Season a few weeks in, let’s take a look at 5 relief pitchers that have impressed thus far and are due for career years!
Justin Slaten
Don’t let Justin Slaten’s 4.00 ERA fool you. He has some of the most dominant stuff in baseball which he supports with an uncanny ability to pound the zone. His arsenal is highlighted by a high riding cut fastball that saws off bats and induces extremely weak contact. He pairs it with quite possible the best set of secondaries of any pitcher in the Majors. His cutter is yet another damage mitigating offering that Slaten uses early in counts to rack up strikes. It currently has a 67.6 Zone% and that doesn’t even matter because batters have a difficult job with making solid contact against it.
His sweeper and curveball are the cream of the crop breaking balls as they exhibit high end velocity with a ton of movement. He does an excellent job at locating them at the bottom of the zone, making it no surprise that they have returned some gaudy whiff numbers.
I have been saying Slaten is the best reliever in Boston for over a year now and he keeps on proving why. He has converted a handful of save opportunities already and I would not be surprised if he leads the team in saves by season’s end.
Kyle Leahy
Kyle Leahy was my “breakout” pick for the Cardinals this season and he is making me look like a smart man early. He currently has a 1.72 ERA and 0.45 WHIP across 15.2 IP, making him one of the most valuable relievers. His sweeper is the crown jewel of his arsenal, sitting 85-87 MPH with 15” of sweep and grading out as a beautiful 124 tjStuff+. The rest of his arsenal is jam packed with intriguing offerings, all of which Leahy commands well and alternates between to tackle any batter.
His fastball is vastly improved this season. While its velocity is down ~1 MPH, he supplemented it with an extra +1” iVB and more cutting action to shoot its tjStuff+ from 102 to 109. His 90 MPH slider works in tandem with his sweeper to pack up RHH, where his changeup and curveball are effective weapons against LHH. His new sinker has been extremely effective in the early going as a damage mitigating pitch which Leahy repeatedly fly pounds inside to righties.
Leahy has seen a large jump in his stuff this season while showcasing solid command. He has a starter’s arsenal while working in high leverage situations for St. Louis and is excelling. He might not get the chance to join the rotation this season, but if I had to guess the next successful RP to SP conversion, Leahy would be near the top of the list.
Ryan Zeferjahn
Ryan Zeferjahn has struck out over 50% of the batters he faced thus far, and he is doing do in and absurd manner. His 40.7 Whiff% indicates that he is earning his Ks and his stuff supports the results. His primary offering a high 80s cutter (really a slider) that essentially lives in the heart of the zone. He has allowed a bit of hard contact on the offering, but its ability to generate whiffs while having a 71.2 Zone% signals that Zeferjahn shouldn’t have issues with strikeouts.
Another positive aspect of his ability to fil the zone with his cutter early is how often he gets ahead in the count. Against the 27 batters he has faced this season, he has yet to reach a 3-0, or 3-1 count. He does not put himself into a position to give up free passes without the chance of a strikeout present.
It is quite confounding how erratic Zeferjahn is with his fastball and sweeper which he tends to use as put away offerings. Seeing that gets ahead quickly with his cutter, it’s not too big of an issue when he misses his spots, but it is something that could limit his ceiling.
Zeferjahn’s approach makes me believe that he can be a premiere strikeout arm in the majors, and could pick up a handful of saves throughout the season.
Yimi García
Yimi García always gives 100%. He is a blast to watch, and his results with the Blue Jays speak for themselves. This season he owns a 0.00 ERA and 1.44 FIP across 11.1 IP while operating as Toronto’s set up man.
He approaches consists mainly of his 4-seam fastball about half the time to both handedness and then a medley of secondaries depending on the situation. Each of his pitches flash plus characterises and he elevates their effectiveness with his tendency to throw strikes. His fastball has been particularly deadly against RHH, returning an ungodly 57.1 Z-Whiff%.
With such a good fastball, García’s floor seems stable as a medium-to-high leverage arm. When you consider that he has 5 other pitchers all with strong qualities that he commands well, it is quite easy to see why is one of the most effective setup men in the league. The Jays needed some bullpen reinforcements, and García is one of the best.
Shelby Miller
Shelby Miller may have the best fastball in MLB. Yes, that “Shelby Miller”. His fastball has been a key piece of his success to stary the season. He currently holds a 0.00 ERA and 2.06 ERA across 10.1 IP with fantastic pitch metrics and results to back it up.
Miller’s fastball has all the characteristics you want to see from an elite offering:
Velocity
Extension
iVB relative to slot
Command
While his velocity is simply average (94-95 MPH), he does the 3 other aspects at an elite level. His 7.1 ft extension sits him amongst the best in baseball and his 18.0” iVB from a 5.4 ft release height is outstanding. These traits form the basis of an excellent fastball, and his command pushes it over the edge. He has a knack for locating it high in the zone where batters cannot keep up with its high riding action.
The fastball isn’t the only tool in his belt. Miller’s splitter is vastly improved this season as it is getting an additional +1” of vertical separation of his fastball. This change bumped up its tjStuff+ grade from 97 to 103 and has helped the pitch yield a +3 RV in fewer than a dozen outings.
With AJ Puk on the IL and Justin Martinez dealing with shoulder soreness, look for Shelby Miller to swoop in a close out games for Arizona. His fastball alone makes him one of the most interesting RP in baseball this season!
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