Diamondbacks 2025 Player Projections: Justin Martínez

Why Martinez may outperform the projection

Martinez is coming off a dominant year in his first full season. He pitched to a 2.48 ERA in 72.2 IP. At only 23 years of age, he has set himself up to break out into a great closer in the coming seasons.

A large part of the righty flamethrower's success last year stemmed from his improved walk rate. While his career BB/9 still sits at a poor 5.1, due to a humungous 9.9 BB/9 in 2023, his improvements in attacking the zone have been phenomenal. He halved his walk rate to 4.5/9 in 2024.

Martinez's FIP does not suggest much regression. While his career FIP is significantly better than his career ERA (3.12 FIP compared to a 3.70 ERA) much of this comes from his limited 2023 sample. There, he posted just a 36 ERA+, with a 12.60 ERA and a 6.96 FIP.

In 2024, however, his FIP sat higher than his ERA, with a 2.59 FIP compared to a 2.48 ERA. There isn't much variance in last year's number, and by projections, this seems to stay the same, with a projected 3.32 FIP and 3.28 ERA.

Martinez's pure stuff is the stuff of dreams for any pitching coach. He brings a 4 pitch mix which primarily consists of a sinker, slider, and four seam combination, with a devastating split finger fastball that he throws 22% of the time.

2024 was a step in the right direction for Martinez, moving past his control issues and quickly transitioning into a back end reliever. Through August 20th of last year the right hander boasted a 1.79 ERA, with opponents only hitting .199 against him, with a .540 OPS.

His home run rate was another large step forward, with only 0.2 HR/9 in 2024. Projections dont see this as sustainable, with our line reaching 0.94 HR/9 innings in 2025. This is an area where Martinez may exceed expectations.

The right hander's stuff is incredible, and relying primarily on a sinker that often crosses into the 100 mph range, it is difficult for opponents to elevate the ball against him.

Why Martinez may underperform the projection

Youth can be both a blessing and a curse. The 23-year-old righty is still fresh out of the minor leagues, and while he has accrued some back-end experience in his short major league tenure, it seems that the team isn't quite ready to pass him the reigns.

With only 9 career saves (8 in 2024), he is still new to closing out ballgames, and emotions can change things quickly. Collecting a save is one of the most mentally tough things in sports, and for a young player still finding his way, Martinez may still hit some turbulence.

Next season is a big one for the young reliever as he will likely be granted a far longer leash. It is still uncertain whether or not he will be utilized in a closer role, with the Diamondbacks reportedly being in the market for back-end relief help. Still, Martinez will see high-stress innings and will need to prove his ability to get outs in the biggest moments.

Our projection is quite bullish on Martinez's ability to take another step forward in the walk department. This may not come to fruition. A big step for him in 2024 was limiting free passes, but at a staggering 5.4 fewer walks per 9 in 2024 than in 2023, we may see the right-hander battle with some regression.

Summary

Control and nerves will dictate much of Martinez's fate in 2025. Last season showed his potential, with a dominant strikeout rate meeting a much improved walk rate. While his utilization next season is still unclear as of now, he will see high leverage innings, and these will be a large proving ground for the right hander.

Projections do view Justin Martinez favorably, with Steamer projecting the flamethrower to rank 14th in ERA. Still, there is a world where past walk issues and inexperience show how difficult a reliever's job truly is. In a game where one poor week can dictate a season-long storyline, he will have a lot to prove.

Justin Martinez has shown that when he is on his game he can be one of the best relievers in baseball. While he may not be ready to step into a closer role yet, he will still headline an exciting D-backs bullpen, where he may go on to have his best season yet.

For more in-depth breakdowns and up-to-date news, stay locked into all things Arizona Diamondbacks ON SI.

Related Content

Player Projections: A.J. Puk

Player Projections: Eduardo Rodríguez