Shelby Miller and Kevin Ginkel could lead Diamondbacks' bullpen with Justin Martinez on the injured list

A baseball season can often be a war of attrition. A 162-game schedule is a grind for any team, and when the cold streaks or the bumps and bruises start to pile up, the teams that can weather the storm most effectively are often the teams that will put themselves in a position to be hoisting a trophy at the end of the year. The Arizona Diamondbacks find themselves in such a position right now.

With Jordan Montgomery out for the season following Tommy John surgery and All-Star second baseman Ketel Marte and co-closer AJ Puk already on the IL, the Diamondbacks were dealt another tough blow on Thursday when they were forced to place their other closer, Justin Martinez, on the 15-day injured list with right shoulder inflammation.

Martinez saved eight games for the Diamondbacks in 2024, pitching to a 2.48 ERA and 1.31 WHIP while striking out 91 batters in 72 2/3 innings. The 23-year-old looked electric in spring training, darting 104 mph fastballs by hitters, and began the 2025 season with a 2.70 ERA and 11 strikeouts in 10 innings while picking up three saves as a co-closer with AJ Puk.

However, last weekend, Martinez’s sinker, which usually averages 100.7 mph, was down to 97.9 mph. He was able to pitch around a few baserunners to secure a save in his next performance, but on Wednesday night against the Mets, Martinez was averaging 93.5 on his sinker and allowed three baserunners before being pulled from the game.

“I was clear last night, right?” said Diamondbacks’ manager Torey Lovullo before Thursday’s contest against the Mets. “We were all watching the same thing, and the stuff was down, so we called [Martinez] in and had a really nice, deep discussion with him. We just figured this was the best option for him to get back to Arizona, get evaluated by our medical team, and let’s find out what’s going on in his shoulder.”

As of Thursday, the team is simply saying that Martinez is experiencing fatigue in his shoulder, and Martinez himself “feels strongly that there’s nothing wrong,” according to Lovullo. Still, the team will get imaging done and allow Martinez the time and space to rest, and then, provided the imaging comes back clean, work to get their young closer back up to speed.

“He said he’s not sure why it’s fatigued,” explained Lovullo. “He was working hard to strengthen [the shoulder], but through that, maybe overdid it a little bit, over-baked it a little bit. That happens, but we’re going to remain optimistic that everything’s clear. Just a little bit of a rest is going to get him back up to speed.”

So, with both Martinez and AJ Puk on the injured list, who will be taking the ball in the ninth inning to close games for the Diamondbacks?

“I know everybody’s gonna ask me who’s gonna be closer,” smiled Lovullo. “I don’t know what that answer is... We have a very capable bullpen, a very deep group of guys that we trust. We miss AJ, and we’re going to miss J-Mart, but they’re going to heal, and they’re going to come back, and they’re going to help us win games. But in the meantime, everybody’s going to hold down the fort, keep their seats warm for them, and help us win baseball games.”

The three names that Lovullo mentioned specifically were Shelby Miller, Kevin Ginkel, and Ryan Thompson. “When these guys step on the mound, they’re prepared,” said Lovullo. “They know what it smells like, and looks like, and feels like.”

Thompson is a side-armer who registered the final outs on Wednesday night in the win over the Mets when Martinez had to be lifted from the game. He has eight saves in his MLB career and currently ranks 5th on the team in Game Leveredge Index, which is a Fangraphs stat that measures the average leverage (or how important to the game) a situation is when the pitcher comes into the game. Given that, it would seem that Thompson is likely just an ancillary option to close games.

The pitcher with the highest Game Leveredge Index score on the Diamondbacks, the pitcher who has pitched in the biggest spots this season, is the new addition to the bullpen, Shelby Miller.

“His emergence and his growth from the last time I saw him has been enormous,” said Lovullo. “He’s executing pitches at a very high level and getting huge outs for us.”

On the season, Miller has yet to allow a run on four hits in 12.2 innings while striking out 15 and walking four. It’s been quite the resurgence for the former 19th overall pick in the 2009 MLB draft, who posted a 4.08 ERA in 735 MLB innings as a starting pitcher before officially moving to the bullpen in 2021. He pitched mainly low-leverage innings early on, acting as a multi-inning reliever, before finally getting thrust into some medium and high-leverage spots with Detroit last season.

“Nothing really changes too much,” Miller said of his shifting roles over his career. “Being in the pen, you kind of have to be ready for any situation at any time. The preparation part stays the same: just go out and you have a game plan and attack hitters with the best stuff you got.”

That stuff for Miller in 2025 has included a few changes to his arsenal, like modifying the shape and attack plan on his splitter.

“I killed some vert on the split,” he explained before Thursday’s game against the Mets. The pitch now has 1.5 inches less vertical drop but slightly more horizontal run, which has given it more movement overall. However, the bigger change is that Miller is no longer as focused on using it early in the count. Last year with Detroit, Miller threw his spitter early in the count 63% of the time and only 32% of the time in two-strike counts. It had just a 36% zone rate and an 11% called strike rate, so the choice to use it early in the count is a bit perplexing. This season, he’s throwing it early in the count just over 44% of the time, while using it in two-strike counts 51% of the time.

The PutAway rate on his splitter, which measures how often a two-strike pitch results in a strikeout, has jumped 4%, and the overall swinging strike rate is up 7% to 21.3% overall. Much of that may have to do with how often he’s attacking low in the strike zone. This season, he’s throwing his splitter in the lower third of the strike zone or below it 83% of the time. He did that just 70% of the time last year. So even though the overall zone rate on the pitch is worse, the approach is working much better for Miller.

“When my splitter is good, I really don’t want to throw for a strike,” Miller confirmed. “The key to any kind of pitch is just to have a look. They talk about tunneling and stuff, so just tunnel it off of your fastball. You want everything to kind of be in the same zone as late as possible and break from there. So there will be times where I need to throw a split for a strike, but that’s not necessarily what I’m trying to do.”

Another change that has worked for Miller has been bringing back his sweeper.

“Last year, when I was in Detroit, they wanted me to go to kind of that gyro or bullet slider, and I didn’t really have very much success with it against right-handed hitters,” he explained. “I stopped throwing that this year, and I’ve gone back to the sweeper, which is just something that’s a little slower, which is nice for a change of pace.”

Miller’s sweeper is averaging 15.2 inches of horizontal movement at 82.6 mph compared to his slider last year, which had just five inches of horizontal run at 88.3 mph. The sweeper has only posted an 8.3% SwStr% compared to a 12% mark on the slider last year, but Miller sees the value of the sweeper being more than just swings and misses.

“It’s about speed and shape,” he said. “It’s just a different look to right-handed hitters, and then obviously using the split and heater off of that... It’s not like an elite pitch by any means, but it’s just something to be able to show and throw for a strike and get ahead in counts, and then, when it calls for it, to expand with it. There’s gonna be hitters that swing and miss off of it, so it’s just a nice pitch to have a bigger shape to be able to use.”

The changes to the arsenal that helped fuel this breakout have also put Miller in the position where he may be called on to get the final outs of the game. It’s a challenge that he welcomes.

“Whenever my name is called, whatever inning it is, I’ll be prepared,” said Miller. He knows that being a good closer takes “confidence in yourself and your stuff, and then after that it comes to execution.” But that level of confidence is something Miller feels when he steps onto the mound right now, and he has every look of the kind of pitcher you’d want to slam the door on the opposition for you.

However, that could also work against him if you’re projecting out saves since Lovullo could continue to use him in the highest leverage situations, even if they happen to be in the sixth or seventh inning. If that were to be the case, then Kevin Ginkel would emerge as the favorite to rack up the most saves in the Arizona bullpen until Martinez and/or Puk return.

The 31-year-old saved five games for Arizona last season and was in the mix for the closer’s role during a strong spring training before shoulder inflammation landed him on the IL. He made his season debut on Wednesday night and was immediately thrust into a high-leverage spot, coming into the game with two out in the seventh inning, the tying run on first base, and the heart of the Mets order coming up. He walked Pete Alonso but struck out Mark Vientos to preserve the lead for Arizona.

“I feel great,” said Ginkel after his performance. “It was a good outing yesterday. A critical spot in the game to come into, but overall felt great. It was cool to be in a spot like that and deliver for the club... The biggest thing was coming back and feeling good and bouncing back after an outing. I think the hardest thing as a reliever is when you come back from an injury, getting back into the flow of the game, and getting back into your routine, so, for me, last night was moment where I’m like, “Okay, I feel like I’ve mentally and physically prepped.” From the third inning on, I felt like I was ready for that situation, wherever, whenever it came up.”

The veteran has been ready whenever his name is called many times in his Arizona career, which is why his manager knew that he could turn to him right off the injured list. “I knew [Ginkel] was going to get back in that saddle right away because of that experience,” said Lovullo. “He’s already pitched at the highest level in the biggest games, and he’s a leverage guy for a reason, and I knew he’d step into that and succeed.”

Being a “leverage guy” also means that Ginkel won’t strictly be used in the ninth inning, and that’s OK with the veteran.

“To me, it really doesn’t matter,” he admitted. “There’s been times, countlessly, that I’ve come into games in the fifth or it’s been in the eighth with two outs, so it really doesn’t matter because there’s moments in the game where that momentum shifts to the other side and it’s hard to regain that momentum. Being able to keep that energy and that momentum in our dugout is critical. Anytime you can leave runners stranded or put up a big zero after we score, it’s a big deal.”

But, much like with Shelby Miller, if Ginkel’s name is called in the ninth innings, he’ll be ready to do his job.

“I definitely have appreciated pitching in [late inning] spots and delivering for the club. Getting the last three outs in the game is really tough. I’ve had some experience now doing it, but I know that’s not up to me. However [Coach Lovullo] wants to do it with Martinez out now going forward, I’m open to it. As long as we keep winning, that’s all I really care about.”

The next few games will give us a better understanding of how the Diamondbacks are going to deploy their bullpen, but early usage patterns seem to point to Shelby Miller being used to get the highest leverage outs with the game hanging in the balance. Sometimes that will be the ninth inning, but other times it could be in the seventh or eighth. In those instances, Ginkel would likely be the favorite to come in for the ninth inning and secure the save, but Ryan Thompson will also hear his name called when they don’t want to put too much strain on Ginkel’s shoulder.

For fantasy purposes, that might make Shelby Miller the priority add given his success so far this season, but Kevin Ginkel should also see enough save opportunities in the coming weeks to be valuable in most league types as well.