While the starting rotation has been an up and down entity a month or so into the 2025 MLB season, the D-backs bullpen has also been an adventure to navigate. If there’s one reliable part of it, it’s the back end of it in A.J. Puk, Justin Martínez, Shelby Miller and Jalen Beeks. Unfortunately Puk, who was already injured with a left elbow flexor strain, was transferred to the 60-day IL and Martínez to the 15-day IL with shoulder inflammation on Thursday morning.

With the two of those pitchers going down for the foreseeable future, the D-backs will need to look both internally and perhaps externally for reliability in high leverage situations. With that in mind, let’s take a look at three players who could fill the closer role.

Shelby Miller

The casual fan likely remembers Miller for the disastrous trade which sent out former number one overall pick Dansby Swanson for Miller. In his initial three seasons in the desert, he pitched to a 6.35 ERA in 139 injury riddled innings as a starter. Since being given a chance as a full time reliever in 2023 with the Los Angeles Dodgers, Miller has become an effective bullpen piece with a 142 ERA+, 3.88 FIP, a sub-1.00 WHIP and nearly 9K’s per nine innings.

Miller was just an “ok” pitcher last year on a Detroit Tigers squad that made the playoffs. This year he’s much closer to his 2023 self, having not allowed an earned run all year to this point. He’s done it in part due to modifying his splitter. Now, the D-backs reliever has subtracted vertical movement from the pitch but added horizontal movement. On the vertical side, there’s 1.3 inches less vertical break whereas on the horizontal side, there’s about half an inch more to the glove side. It may not sound like much, but it’s been making all the difference. It’s tripled his swinging strike rate on the pitch from 7 percent last year to 21 percent this year.

The only thing working against Miller in terms of being a full-time closer for the D-backs is just how effective he’s been. It would be more wise to have him reserved for the highest leverage moment in a game rather than saving him for the ninth inning.

kevin Ginkel

Of the three options we’re looking at, Kevin Ginkel has the most closing experience with 13 career saves, five of those coming in 2024. Ginkel has been with the D-backs and manager Torey Lovullo since 2019, giving him seven years of trust and experience to build upon. It’s one thing to throw out a newer arm like Miller, but one of the biggest components of crafting a bullpen is having arms you can trust, and Ginkel has clearly built that with Lovullo.

This trust was shown when Ginkel faced top of the Mets order on Thursday afternoon, but he gave up a homer to Juan Soto, walked Pete Alonso and allowed a double to Jesse Winker. It may have been a messy inning in only his second appearance since returning from a stint on the injured list, but he did manage to get strikeouts on all three outs of the eighth inning.

In total the bullpen has a 4.64 ERA and until Miller had closed out Thursday’s game, had blown every save five of 13 save opportunities. With the trust Ginkel has established, he could be the go-to option in the ninth.

Ryan THompson

The third name Lovullo mentioned could get opportunities was Ryan Thompson. Thompson got the opportunity on Wednesday in what was a thrilling inning. With Martínez not on his game and throwing well under his usual velocity, it was Thompson who got the call out of the ‘pen. With the tying run on base, Thompson didn’t fold under the pressure and allowed just one run, which was charged to Martínez, and nabbed the save for the D-backs. Thompson may be the least likely candidate for saves, but he’s still in the mix.

The side-armed pitcher employs a wicked slider/sinker combination to get his outs. The slider is the pitch he uses the most and it often performs like a sweeper would given it somewhat lacks any vertical break to it. What makes it effective is the pitch breaking 9.6 inches more than the average slider thrown this year.

Like many sidearmed pitchers, Thompson is not an exceptionally hard thrower; his fastball velocity sits in just the sixth percentile. However, he’s able to get outs by limiting hard contact which sits in the 92nd percentile of MLB and getting players to chase pitches, sitting at the 96th percentile in MLB. He does this with the aforementioned slider’s attributes as well as a sinker which breaks over a foot more than the average MLB sinker thrown in 2025.

Regardless of whether it’s Miller, Ginkel or Thompson emerging as the closer option for the D-backs, being without their two best options in the bullpen for a while could either spell doom or an opportunity for further breakouts in unexpected places.