How Much Will Seth Martinez Contribute to the Diamondbacks in 2025?

Why the veteran reliever could play a bigger role than expected next season

May 15, 2024; Houston, Texas, USA; Houston Astros pitcher Seth Martinez (61) pitches against the Oakland Athletics in the eighth inning at Minute Maid Park. Mandatory Credit: Thomas Shea-Imagn Images / Thomas Shea-Imagn Images

As we continue through our series of 2025 Diamondbacks projections we take a look at newly acquired Seth Martinez. The veteran right-hander will join Arizona's bullpen and could play a key role in 2025.

Seth Martinez projection / Alex D'Agostino

Why Martinez could surpass projections

After being claimed off waivers from the Houston Astros, Martinez will join an Arizona bullpen that faced significant struggles in 2024.

The right-hander is projected to finish 2025 with an ERA of 4.26, a number far worse than his performance last season. Coming off a year which wasn't great with Houston but still saw Martinez find some success, a drop-off of over half a run of production would be terrible.

While 2023 was a comparable season of production to what projections predict Martinez to finish with next season, his precedent suggests that he may be in for a better year.

2022 is the best season in the right-hander's career to this point, putting up a 2.09 ERA in 38.2 IP, and after stumbling the next season, 2024 was a solid season for Martinez.

To this point in his big league tenure, he has had more good seasons than bad, and while his ERA+ of 111 last season likely won't blow anyone away, it could make Martinez a productive member of the Diamondbacks' relief group.

Walks were a large part of Martinez's failed 2023 season. There he fell from a 3.3 BB/9 to a far worse 4.0 BB/9. While his solid strikeout rate worked to counteract this, the additional free passes certainly didn't help with his overall struggles.

A season later he found himself pitching to a career-best walk rate with only 3.1 BB/9 and did so in a career-high innings total. This return to form command-wise was likely a factor in why Mike Hazen and the Diamondbacks chose to pick up Martinez.

Why Martinez may fall short of projections

While 2024 brought some improvements for Seth Martinez, including the return of his command and a significant drop in walk rate, his strikeouts took a significant hit.

Having sat steadily at an average K% of around 23% in 2022 and 2023, something shifted last season. His ERA improved significantly from a year prior, but his ability to miss bats and get outs via the strikeout dropped drastically.

This number fell all the way to 16.2%, or 7% down from the year before.

Projections see him taking a small step in the right direction, climbing to 19%, but even this is well below league average and would hurt his ability to get outs. At 30 years old now, Martinez will need a big turnaround in strikeouts in order to rebound in his production.

Another year of below average production, or even further regression, would leave his future in jeopardy.

Another point of concern in Martinez's arsenal is his significant FIP discrepancy. In 2024 his 3.59 ERA was a world apart from his 4.78 FIP, suggesting some serious potential for regression.

While his drop in strikeout rate likely played a role in this, his 1.19 run differential between the two numbers sends up quite a few red flags. This isn't the first time that the right-handers FIP has been far apart from reality though.

In 2022 his stellar 2.09 ERA was once again in the shadow of a menacing 3.32 FIP. This season was followed by a terrible 5.23 ERA regression. While it is unclear if 2025 will see a similar pullback to the mean, his large difference in underlying numbers doesn't instill complete confidence.

Summary

Martinez is a solid addition to Arizona's bullpen group. His improvements in control last season bode well for a potential rebound, to his 2022 form, or even just a continuation of his middling numbers.

His ability to post and give the D-backs some solid work in middle relief will raise the floor of the club's bullpen, and give them an opportunity to focus their attention more towards the back end for further additions.

This as well as an addition of a veteran presence who has been around a competitive environment in Houston for the last 3+ seasons could add a positive influence to a younger group of relievers such as Justin Martinez and Drey Jameson.

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Arizona Diamondbacks 2025 Player Projections Links Hub

Diamondbacks claim RHP Seth Martinez off Waivers from Astros