Looking Back On Four Breakout MLB Candidates For 2024
Image credit: Triston Casas (Photo by Eddie Kelly / ProLook Photos)
Back in February, we profiled four MLB players who were set to go from good to great in 2024. The results were… mixed.
What went wrong? And who of this quartet has the best chance at rebounding in 2025 and beyond?
Triston Casas, 1B, Red Sox
Casas had the best year of the original group, which is disappointing considering he was limited to 63 games and had a lower wRC+ (119) than he did as a rookie in 2023 (130).
In some ways, Casas’ year never got off the ground, as he suffered a rib cage injury on April 20. Before the injury, he slashed .244/.344/.513 with six homers and a .269 ISO. Only Mike Trout and Marcell Ozuna had more homers at the time of his injury. It was just 90 plate appearances, but the promised breakout appeared to be coming to fruition.
After returning on August 16, Casas hit .242/.333/.439 with seven homers and a .197 ISO, which meant he was 12% better than league average with the stick. However, he admitted that he was still playing through some pain.
Given that neither partial-season performance is a big enough sample to buy into, it’s hard to look at Casas’ 2024 results with anything other than a shrug.
Process-wise, Casas is now two seasons removed from the extreme passivity he displayed in his 2022 big league debut. This hitter once admitted to chasing OBP over SLG in the minors. It’s entirely possible he was getting his feet wet in Boston that year.
Using Robert Orr’s metrics, Casas improved at taking fewer “hittable pitches” in 2023. That trend went backward in 2024, though the missed time and injury could’ve had something to do with it.
Ultimately, Casas is only entering his age-25 season and has a proven ability to get on base with thunderous raw power. Recall that in July 2023, he hit the longest opposite-field homer by a lefty in Oracle Park in the Statcast era:
Casas still has room to grow with the amount of hittable pitches he lets go by. Sacrificing some “chase” to get his barrel on the ball more often could be his path to stardom. 2024 was a letdown, partially due to reasons outside of his control, but his ceiling at the plate remains as high as it was at this time last year.
Royce Lewis, 3B, Twins
Lewis entered 2024 having played in just 70 career MLB games. In those games, he hit .307/.364/.549 (152 wRC+) with 17 homers and a flare for the dramatic. Fantasy players and Twins fans wondered what he could do in a healthy season.
On Opening Day against the Royals, he homered in the first inning and singled in the third, both off Cole Ragans. It was happening. Then he strained his quad running the bases and wasn’t seen with the Twins again until early June.
In typical Lewis fashion, he homered in his first two games back and hit .276/.340/.644 (171 wRC+) with nine homers in 23 games.
Then, he suffered a right adductor strain. And while he homered in his second game back this time, Lewis ultimately wasn’t the same to close out the year. He slashed .207/.270/.350 (74 wRC+) with six homers in 58 games to end the season.
Per Statcast, here are Lewis’ swing rates before and after his second in-season injury interruption:
- Before: 29% chase, 73% zone-swing
- After: 34% chase, 71% zone-swing
He was possibly chasing more often out of frustration or he wasn’t 100% healthy. That’s the issue for Lewis’ professional career thus far, though—he just hasn’t been healthy.
Before 2024, Lewis’ per-game results hinted at stardom if he could remain on the field. He played regularly from late July through the end of the season. However, he struggled. Lewis’ batted ball metrics and swing decisions suggest he still has all the necessary tools to become a star. Whether or not he can reach that production level and maintain it for multiple seasons is a fair question going forward.
Bobby Miller, RHP, Dodgers
Similar to Lewis, Miller’s first taste of the 2024 campaign couldn’t have gone better:
He was utterly dominant in his season debut. The stat line showed it, and the eye test backed it up. Miller appeared to have it all post-2023, and a Cy Young chase seemed all but assured after his dominant first showing.
In his next two outings, things went off the rails, as Miller allowed seven earned runs on nine hits and five walks over a combined 5.2 IP.
He was diagnosed with shoulder inflammation, made four uninspiring starts in the minors, and then returned to the Dodgers, where he allowed 19 earned runs (with a 9:12 K/BB) in four appearances. He was up and down between the majors and minors the rest of the way, and he also pitched through a knee issue in the season’s final month.
Overall, Miller posted an 8.52 ERA with the Dodgers, with a 1.77 WHIP and a troublesome 11.6% walk rate. Among starters with at least 50 innings, he allowed the highest HR/FB%, and his ERA ranked last.
How did it get so bad so quickly?
It starts with a four-seam fastball with a -10 run value, per Statcast. Miller allowed a .463 xwOBA on the pitch, trailing only Triston McKenzie’s as the worst in the majors (min. 100 PA).
Miller’s velocity dropped from 99 mph in 2023 to 97.6 this past year. He also lost some vertical ride:
Per Eno Sarris’s model, this caused his fastball Stuff+ to drop from 130 to 119. Troublesome, but still a good mark. His slider, which lost over one mph in velocity, also suffered from a worse shape.
The more significant issue, among all his pitches, was his location.
For instance, compare his slider locations from 2023 to 2024:
This is how a pitcher ranks among the worst in the league regarding walk rate and homers allowed.
Based on how electric he looked in his very first start and since he soon went on the IL with his shoulder problem, it’s fair to wonder if his body was never right after his debut. That’s the risk with young arms who throw hard and don’t have a track record of durability.
Staying healthy is his most important goal for 2025. From there, he must show improved command and control to avoid a mid-career transition to the bullpen.
Grayson Rodriguez, RHP, Orioles
The fourth member of our February breakout list was Eury Pérez. While Casas, Lewis, and Miller dealt with injuries, Pérez never even threw a pitch in the 2024 season, as he underwent Tommy John surgery in April.
Instead, we’ll shift our focus to Rodriguez, who—wait for it—also dealt with injuries this past season. However, the 24-year-old was quite effective while healthy.
Rodriguez was profiled before this season, emphasizing how ditching his cutter led to a second-half breakout as a rookie in 2023. Since returning from the minors in the second half of 2023, Rodriguez has made 33 starts with a 3.35 ERA, a 3.31 FIP and a 3.62 xFIP.
Here are his MLB ranks during this stretch (min. 190 IP):
This is out of a sample of 70 starters, so Rodriguez has a high, above-average floor. In specific metrics, such as generating swinging strikes and limiting homers, he’s been elite. Ranking first in fastball velocity during this time was a surprise, but that’s partially due to how many high-velo hurlers have missed time of late. Also, factoring in the second half of 2023 prevented Hunter Greene, Paul Skenes, Jared Jones and Garrett Crochet from qualifying.
In 2024, Rodriguez dealt with shoulder inflammation in early May and then a lat strain in late July, ending his season.
He allowed 6+ earned runs in three starts and never allowed more than three in his other 17 outings. It isn’t wise to remove one’s worst outings and treat the remaining stats as an actual baseline, but it’s clear there’s more statistical upside for Rodriguez if he can avoid the blowups.
After totaling 122 and 116 innings, respectively, over the past two years, an ace-level workload is the only thing standing between Rodriguez and being recognized among the game’s best in 2025.
