One of the bigger storylines for the Arizona Diamondbacks will be their bullpen. The most important question is who will close for the Diamondbacks in 2026. Arizona Sports radio host John Gambadoro floated one name that should be under further consideration.
“To me, it’s my opinion, I think the best case scenario is [Jonathan] Loaisiga is healthy because he’s got the best stuff,” said Gambadoro on Burns & Gambo‘s episode for February 17. “He’s got swing-and-miss stuff, his ball misses bats. I like a pitcher whose ball misses bats, because I need that strikeout ability.”
Loaisiga is a name to watch in the Diamondbacks bullpen. Arizona took a minor league flyer on the flamethrower, who hasn’t been healthy over the past three seasons. The 2025 season was his healthiest, as he appeared in 30 games and pitched to a 4.25 ERA in 29.1 innings.
Why Jonathan Loaisiga Should Be Considered a Closer Candidate
Diamondbacks general manager Mike Hazen said they are still working out the back of their bullpen. The acquisition of Paul Sewald, their former closer, gives them a more experienced option. But they’ll also consider Kevin Ginkel and Ryan Thompson.
While Gambadoro points out the need for swing-and-miss at the back of the bullpen, it’s more about stuff than results. Loaisiga averages just under 97 MPH between a four-seamer and sinker. He complements them with a cutter, curveball, and a changeup. Hazen mentioned stuff as a big reason why he pursued the former Yankees flamethrower.
Loaisiga misses bats at a fairly healthy rate. In 2025, he produced whiffs on 26.8% of swings and induced chases on 40.6% of pitches outside the strike zone. It translated to just an 18.5% strikeout rate, but perhaps there’s more to be unlocked.
While Sewald has a closer pedigree that the Diamondbacks are familiar with, even they can’t feel comfortable sending him out there. The veteran reliever battled shoulder troubles in 2025, which limited him to just 22 appearances. His four-seamer averaged a career-low 90.4 MPH. Sewald was left off the Detroit Tigers‘ ALDS roster.
Considering the other candidates out there, it makes sense for the Diamondbacks to give Loaisiga the most opportunities to land the closer role out of spring.
How the Diamondbacks Can Unlock More Strikeouts out of Jonathan Loaisiga
While Loaisiga has excellent raw stuff, the problem lies within his pitch usage. He’s very reliant on that 96.8 MPH sinker, with a 67% usage rate vs. right-handed hitters and 43% against lefties. The sinker yielded a .300 batting average, .500 slugging percentage, and a .378 wOBA against opposing hitters in 2025.
The expected metrics, which only account for batted ball data, showed that Loaisiga’s sinker should have performed better. It should still be a featured pitch, especially to right-handed hitters. He complements that with a curveball that takes a sweeper-like shape; perhaps it’s a misclassified sweeper. The changeup also takes the same shape as his sinker, which gives him a three-pitch mix.
Against left-handers, he’ll need to add more swing-and-miss. He struck out just 15.7% of hitters. The changeup is a key pitch, and it’s 40% usage rate works fine. But he doesn’t set up the pitch as much as he could. Ramping up the usage of both his cutter and four-seamer gives hitters a different line of sight and also keeps him off guessing for an arm-side breaking pitch.
If the Diamondbacks can make the necessary adjustments to get more swing-and-miss to Loaisiga, it gives them the potential bridge closer they need to survive the early season. Arizona will be waiting anxiously for A.J. Puk and Justin Martinez to return from elbow surgery. If Loaisiga proves to be the backend reliever they need, the Diamondbacks could make a surprise run in 2026.
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