Arizona Diamondbacks 2024 Player Review: Justin Martinez

The flame throwing rookie reliever showcased his potential and how he could be the closer of the future for Arizona

May 29, 2024; Arlington, Texas, USA; Arizona Diamondbacks relief pitcher Justin Martinez (63) delivers a pitch to the Texas Rangers during the eighth inning at Globe Life Field. Mandatory Credit: Jim Cowsert-Imagn Images / Jim Cowsert-Imagn Images

This article is part of a series chronicling the individual seasons of players who appeared for the Arizona Diamondbacks in 2024.

Reviews for players who still have rookie eligibility for 2025 will appear in our prospect season reviews. Players are presented in the reverse order of their aWAR, an average of Baseball-Reference and FanGraphs WAR.

Justin Martinez, Right-Handed Reliever, Age: 23

2024 Contract Status: $742k, Pre-Arbitration

Justin Martinez 2024 and career stats, both with the Arizona Diamondbacks / Jake Oliver

Justin Martinez was signed out of the Dominican Republic as an International Amateur Free Agent in March of 2018 and since then has made a steady climb to the Majors as a high-potential reliever with plenty of velocity.

He made a cup of coffee debut over 10 games in 2023 before getting left off the Opening Day roster in 2024. While it took a couple of weeks for him to get the call up to the bigs, he dominated in Triple-A.

Once he got called up on April 17, he pitched three scoreless innings over two appearances before getting sent back down. However, on April 23, he was called up for the last time.

Starting from April 17, Martinez put on a show on the mound as he crushed his opponents and allowed just one run over his first 25 innings, through June 14. He had a 0.36 ERA, 2.61 FIP, .174 opponent batting average, 15 hits, 14 walks, and 28 strikeouts.

Truly, the walks were the only issue as Martinez learned how to control his new splitter, his slider, sinker, and fastball.

Regression to the mean hit Martinez from June 15 to August 20 as he still did quite well, but wasn't putting on a display of sheer dominance.

Over those 28 games and 30.1 innings, Martinez started to be used more often in late-game situations and save scenarios, earning four saves out of five chances.

He had a 2.97 ERA, 2.71 FIP over this time period with 24 hits, 10 earned runs, 15 walks, and 39 strikeouts with just one home run allowed. Despite the many baserunners, Martinez was adept at avoiding the long ball and giving up weaker contact.

From August 21 to the end of the season, the numerous multi-inning outings, high-leverage work, and the long first full season in MLB had appeared to start to take its toll on a potentially fatigued Martinez. In 14 of his first 48 games, he threw more than an inning, sometimes three.

He gave up a run or more in eight of his final 16 outings, but still recorded four of five save chances and threw 17.1 innings with more than one inning in five outings. He allowed 20 hits, nine earned runs, seven walks, and struck out 24 and again gave up just one home run.

His ERA over this stretch was 4.67 but his FIP was a strong 2.36 so perhaps he was bitten by some bad luck. Whichever it was, it was a tough time for Martinez to struggle with limiting runs with a tired bullpen in the stretch run of the season.

With the season over, Martinez allowed 59 hits, 20 earned runs, just two home runs, 36 walks, and struck out 91 over 72.2 innings with a 5-6 record, 2.48 ERA, 2.59 FIP, 3.03 xERA, and 2.88 xFIP.

He struck out 11.3 per nine innings and 29.5% of the total batters he faced. He allowed just 7.3 hits per nine innings and walked 4.5 batters per nine innings, a decent number compared to his 9.9 showing in 2023.

He had eight saves, seven holds, and just two blown saves. He has 40 save potential if he can make the leap to full-time closer.

Despite it being a small sample, he gave up 1.8 home runs per nine innings in 2023 and he dropped that number to 0.2 as he managed to avoid the barrel of the bat and get under or above them. It was a critical skill that if he can maintain into future will only help him more.

2025 and Beyond

2025 Contract status: Close to League Minimum Salary in 2025

Justin Martinez will be experiencing just his second full season in MLB as he just had his rookie year. He still has at least five more years of contractual contract with the Arizona Diamondbacks. As such, he will make close to the league minimum salary next year in his second of three pre-arbitration years.

Martinez is set up for a full MLB Spring Training and should be a lock for a late-game bullpen spot on the Opening Day roster, the first MLB Opening Day of his career. It remains to be seen if he can continue to be the electric flamethrower he was in 2024, but there shouldn't be any reason why he can't be.

The only worries with Martinez is regarding his health. He already has had Tommy John Surgery once. With the amount of innings, appearances, and multi-inning stints, the team will have to be cautious with his arm to keep him healthy and effective.

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