Justin Martinez' Split Finger Could Make Him an Elite Closer Someday

The fireballing reliever is tantalizingly close to breaking out as he gains greater control over his arsenal

Arizona Diamondbacks pitcher Justin Martinez (63) throws against the Los Angeles Dodgers / Michael Chow/The Republic / USA TODAY

During Friday night's 4-2 loss to the Baltimore Orioles, the biggest highlight for the Diamondbacks might have been the appearance by Justin Martinez. He faced seven batters, struck out five of them and had two walks, one of which was intentional. He lowered his ERA to 0.84 in 10.2 innings pitched with 14 strikeouts, and none of the three inherited runners he's had have scored.

Martinez did all this plowing through the middle of the order of the best offense in the American League. It didn't matter if the hitter was left-handed or right handed. Nobody could touch him.

What was perhaps more significant than the results was how Martinez did it. Four of the five strikeouts came on swing and miss from his splitter. The other came on his slider. That pitch more than any other has the potential to be the one that elevates Martinez to an elite closer someday.

Martinez averages 100 MPH on both his four seam fastball and sinker and can top out at 102 MPH. Last year Martinez threw the four seam 60% of the time. But so far this year he's seen almost an exact even pitch usage, throwing each of the four seam, sinker, splitter and slider 25% of the time.

The development of the splitter started during the Arizona Fall League in 2022. Interviewing Martinez at the time, he said that the splitter was allowing him to reach new levels in the swing and miss department. "I've always been able to get hitters to swing and miss," Martinez said. "But now even more here at the fall league because I have my splitter, and the more that I've been using it, it's been getting better. "

The splitter's vertical movement vs. average ranks 10th best in all of MLB. It's the combination of velocity and that movement that make it almost impossible for hitters. Nobody in MLB throws the splitter harder than Martinez' 90.3 MPH average. And the ones that are close to that velocity, including Yoshinobu Yamamoto, don't have anywhere near the amount of vertical movement.

It's been a process for Martinez to gain enough control of all his pitches to get to the point where he can induce the swings. However when Martinez is able to throw strikes with his two fastballs and not leave them in the middle of the plate, hitters become helpless against the splitter and the slider. His whiff, or swing and miss rate on the Splitter is a whopping 52.4% and 46.2% on the slider.

The two pitches also give him out pitches against batters from either side of the plate, as he'll use the splitter more frequently against left hand batters and the slider against right hand batters.

Limiting the walks has been the main hurdle for Martinez of course. Last year he walked 11 batters in 10 major league innings. A cursory examination of his 2024 stat line might lead one to think he hasn't improved much in this area, as he has eight walks in 10.2 innings. But four of those walks came in his first two outings.

In his last six outings, 7.2 innings pitched, Martinez has issued just three unintentional walks while striking out 12. He's given up just one run on six hits and has yet to be homered on this year. Martinez has been used mostly in low leverage situations so far, but last night he put out a fire in the 7th and threw a scoreless eighth to keep a 4-2 ballgame close.

If Martinez continues to throw enough strikes to earn manager Torey Lovullo's trust it's only a matter of time until he ascends to a much higher leverage role, and perhaps some day even take over as the team's closer.

For now the the D-backs have Paul Sewald back and in the closer's role, but he is a free agent after 2024. At the very least, Martinez is on the doorstep to join Kevin Ginkel and Ryan Thompson to create an elite setup crew at the back end of games. That could turn a weakness into a strength, a critical need in the Diamondbacks efforts to get back to the Postseason

Here is a highlight reel from last night's outing. Enjoy.

Justin Martinez Dominates Orioles Lineup
Full story at this linkhttps://t.co/ULEypDDBQM
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— Jack Sommers (@shoewizard59) May 11, 2024