Relief pitchers are the most volatile group of players in baseball. There are countless examples of unknown commodities making meteoric rises out of nowhere and superstars flaming out in the blink of an eye. Often, it’s the same pitcher a few years apart. Several of the most dominant relief seasons in MLB history were nearly impossible to have foreseen beforehand.
Nevertheless, there’s no harm in dusting off the crystal ball and giving it a peek. Some bullpen aces rise from the depths of failed starters or minor league journeymen by complete surprise, but often there are subtle signs of latent potential waiting to be tapped into.
With pitchers and catchers reporting to spring training in about a month, let’s consider what relievers might be walking into camp with a career year at their fingertips.
Relief pitcher breakout candidates in 2025
For this second installment of my 2025 breakout picks, I will follow up my starting pitcher analysis by analyzing relievers bound for breakouts. In my analyses, I will be using a project of mine called LASR (League-Adjusted Standardized Rating) which places all stats onto the same 20-80 scouting scale based on league qualifiers. On the scale, 50 is average and 10 points in either direction is one standard deviation (all data is sourced from FanGraphs).
The relievers I’ve chosen had a wide range of outcomes last season, so a “breakout” this year might look different for each of them. Generally, I am predicting them to take significant steps ahead in their performances, whether that means better results, sustained success over larger sample sizes, or both. So, let’s make a call to the pen (sorry, I had to) and see who’s warming up to surprise us in 2025.
Edwin Uceta
In the 2023 calendar year, five separate teams decided to cut ties with Edwin Uceta, a former Dodgers international free agent signee whose career had produced 40.1 innings of substandard 5.80 ERA ball by the end of that season.
After the Diamondbacks, Tigers, Pirates, Mets, and Cubs all declined to continue their Uceta experiences, he signed a minor league deal with the Rays during the 2023 Winter Meetings.
That move may not have grabbed many headlines — Shohei Ohtani’s deal was announced the previous day and seems to have been discussed a tad more than Uceta’s — but its significance was not lost on Tampa Bay. After they lost several key pitchers to injuries, they needed somebody to step up and bridge the gap, reliably tossing some decent innings and not be terrible.
Instead, they oiled up the gears of the good old Rays development machine and turned yet another overlooked reliever into a bullpen big shot.
Over 41.2 innings in 2024, Edwin Uceta posted a brilliant 1.51 ERA and 1.70 FIP. On the LASR scale, adjustments are made for playing time based on progress toward qualification. For relievers I use 54 innings (one out per team game) as the qualifying threshold, which means Uceta’s already-impressive LASR scores have been slightly neutralized from even higher values.
Some people have differing definitions of “breakout” and might disqualify Uceta due to last year’s dominance. However, with less than 42 innings pitched in 2024, there isn’t enough evidence to sufficiently say Uceta is one of MLB’s best bullpen arms yet. Relievers frequently turn in fluky seasons in similar sample sizes; Bryan Hoeing had an identical 1.51 ERA as a reliever in 2024 and isn’t likely to replicate it.
By labeling Uceta as a breakout, I’m predicting he’s got more in the tank. That doesn’t necessarily mean a drastic improvement on that 1.51 ERA — there’s a limited capacity for progress there — but a comparable performance over a larger sample size is not hard to envision. With a full season of excellence to pair with his 2024 success, the 27-year old would prove to be one of baseball’s best relievers.
There are several factors setting Uceta apart from the wasteland of one-and-done relievers whose magical runs concluded as quickly as they began. The first telling signs are his ERA estimators: his FIP and SIERA both graded out to 70 on the LASR scale, even higher than his ERA. He showed little signs of weakness, with his K%, Prevent BB%, and Prevent HR% LASR scores all at 60 or above.
Breaking down his abilities further, he routinely makes batters whiff, chase, and make soft contact. The largest point against him is that his batted balls lean on the flyball side; however, he produced pop-ups (Infield Flyballs – IFFB) as well as any other reliever in 2024. If those flyballs continue to stay on the infield dirt, where they’re practically as effective as strikeouts, he doesn’t need to be a groundball maven.
The most obvious reason to believe in Uceta’s success may simply be the uniform he’s found himself in. Tampa Bay has made a habit of these rags-to-riches reclamation projects, and indeed have been credited with altering Uceta’s arm slot and pitch mix to help him realize his potential. If these adjustments serve as catalysts to real change, Edwin Uceta may find himself as a top-level high-leverage arm by season’s end.
Robert Garcia
When the Rangers traded first baseman Nathaniel Lowe to the Nationals after he gave them four solid seasons and contributed to a World Series championship, fans likely expected a promising prospect or two in return. Instead, 28-year old left-handed reliever Robert Garcia was sent back to Texas in a perplexing one-for-one deal that left many wondering why the Rangers had set their bar so low.
A portion of the trade’s reasoning was financial considerations. Lowe is set to make about $11 million in arbitration in 2025, and though that is a reasonable price for his services, the acquisition of Jake Burger on a cheap, pre-arbitration contract essentially broadcast the Rangers’ intentions to move on from Lowe. From the outside, the trade looked like an unnecessary salary dump for a replacement-level relief pitcher.
However, a closer look at that pitcher shows potential for the Rangers to get a sneaky win out of this trade.
On the surface, Robert Garcia had a mediocre year in 2024, which was his first full season in the MLB after a half-season debut the previous year. In 59.2 innings, he put together a middle-of-the-pack 4.22 ERA that didn’t make any headlines. Baseball Reference’s WAR, which prioritizes results over peripherals, even measured Garcia as slightly below replacement at -0.2.
However, the version of WAR over at FanGraphs, which focuses more on underlying skills, placed him at 1.5, a noticeably stark difference and a valuable total for a reliever. Suddenly, Garcia looks less like someone who could be replaced by grabbing the nearest reliever off the scrap pile, and more like a meaningful contributor to a playoff-ready bullpen.
The wide gap in these evaluations can be attributed to the two contrasting pictures painted by Garcia’s ERA and FIP. In plain terms, his 4.22 ERA towers over his 2.38 FIP; by LASR scores, we can see that Garcia’s ERA (45) was below league average while his FIP (65) was significantly above league average. SIERA and other ERA estimators (not shown above) all take FIP’s side of the argument.
Garcia was about a standard deviation above league average (60 on the LASR scale) in getting strikeouts, preventing walks, and preventing home runs. He was above average at getting whiffs and limiting high exit velocities, and was particularly skilled at getting batters to chase or miss barreled contact. By most accounts, Garcia had the makings of a rockstar reliever.
Unfortunately, the earned runs stacked up at a higher volume than expected, but there is hope for a turnaround. Garcia received bad luck on batted balls, with a Prevent BABIP LASR grade of 40, and had an atrocious strand rate, with a LOB% LASR grade of 25. While there is a little inherent skill in these metrics, they are largely luck-based and should rebound closer to league average in 2025.
The Rangers acquired Garcia for a reason, and they may have ideas for potential improvements even past a dependence on better luck. He will also benefit from their defense, which ranked 7th in FanGraphs’ Defense metric in 2024 while the Nationals ranked 27th.
With excellent underlying abilities, better luck, and better defenders behind him, Robert Garcia may be a key piece to a Texas push to return to the playoffs.
Nick Mears
I mentioned earlier that there are different definitions of “breaking out” and that I’ve boiled down my choices to players who I predict will take a step up in their performances. For Edwin Uceta, that meant turning a great small sample into an elite larger sample. For Robert Garcia, a breakout would entail a jump from mediocre to indispensable bullpen piece.
For Nick Mears, a 28-year old with a career 5.20 ERA and even worse results in his largest sample size to date in 2024, the breakout bar will naturally be set closer to the ground. After spending a few years bouncing between the majors and minors for the Pirates and Rockies, Mears was acquired by the Brewers last summer and posted a terrible 7.30 ERA during their playoff push.
Believe it or not, though, there is hope to be found amidst the rubble of that disaster.
To be honest, Nick Mears is one of my choices because a valuable season from him would truly seem to come out of nowhere. However, there are signs of the possibility.
Despite his awful ERA LASR of 30 last year, all of his ERA estimators came out above league average at 55. If his results trend in that direction, he won’t necessarily be a high-leverage arm, but he’ll be much more useful than he’s been so far.
He clearly has the ability to rack up strikeouts, with a 60 K% LASR and 55 Whiff% and Chase% LASRs. This upside is also apparent in the raw capabilities of his pitch mix as measured by the Stuff+ model, which places him on the upper end of the reliever pool. The PitchingBot model graded him above average too, albeit to a lesser extent at 55 (not shown above).
As with Robert Garcia, one of the clearest factors in his poor 2024 performance was bad luck. His Prevent BABIP and LOB% LASR grades were both incredibly rough at 30. For reference, that was a .360 BABIP and a 59.8 LOB%, both of which were fourth-worst among relievers with 50 or more innings pitched. Both of those values should regress toward league average in the future.
Mears has shown a couple of concerning weaknesses that should be addressed. First is his control, which produced a below-average 45 Prevent BB% LASR in 2024. His major league walk rates, in fact, have always been bloated. However, they have also been steadily improving, and after his trade to Milwaukee, he only walked three batters in 12.1 innings for a better-than-average 5.7% walk rate.
Another cause for distress is the five home runs he allowed in that small-sample Brewers tenure. Before the trade, though, he gave up a shockingly low two home runs in 45.1 innings in Colorado, where home runs are a dime a dozen. Perhaps he made some adjustments in Milwaukee that led to better command at the expense of more pitches in the heart of the strike zone.
If Mears pitches a full season in 2025, it’s likely his walk rates and home run rates will normalize. The Brewers are another team known for transforming middling pitchers into shutdown relievers, so there is room for optimism that they can help him maintain his improved control while limiting long balls.
With a full season in Milwaukee ahead, Nick Mears could utilize his promising repertoire to become the next nobody-to-somebody success story.