The Diamondbacks announced several transactions in a shake-up of the club’s bullpen mix today. The headline news is that closer A.J. Puk has been placed on the 15-day injured list (retroactive to April 18) due to inflammation in his left elbow. Righty Bryce Jarvis and left-hander Joe Mantiply were optioned to Triple-A, and Arizona filled those three bullpen spots by calling up right-hander Drey Jameson, and selecting the contracts of right-handers Juan Morillo and J.P. Feyereisen. To create roster space, the D’Backs also designated infielder Grae Kessinger for assignment.
Puk excelled after the Diamondbacks acquired him from the Marlins at last year’s trade deadline, and the southpaw has kept going this year by posting a 3.38 ERA in eight innings this season. Even with the benefit of an absurd 97.6% strand rate, Puk has backed up his work with an excellent 34.3% strikeout rate and 5.7% walk rate. In addition to all the swings and misses, Puk isn’t allowing much hard contact when his offerings do find a bat, and he has closed out all four of his save chances this season.
Unfortunately, his strong start has now been interrupted by a trip to the IL. Puk’s lengthy injury history (which includes a Tommy John surgery) puts some extra focus on any elbow-related ailment, though there isn’t any indication at this point that his current issue is anything more than just inflammation. Assuming no structural damage, Puk might be able to return after just a 15-day minimum, though it is just a matter of how long his elbow discomfort continues to linger.
Justin Martinez is now the likeliest candidate to step up as the new closer, with Shelby Miller and Jalen Beeks continuing in high-leverage setup roles. Beeks is also the only southpaw in Arizona’s bullpen now that Mantiply has been sent to Reno.
Arizona’s 13-11 slugfest loss to the Cubs yesterday saw both Jarvis and Mantiply charged with three earned runs apiece, with each reliever throwing two-thirds of an inning. The demotions to Triple-A can allow both pitchers to gather themselves after a difficult start to their seasons, while the D’Backs can get a few fresher arms into the bullpen. This means Jameson is now in line to make his first MLB appearance since the 2023 season, Feyereisen will make his D’Backs debut after signing a minor league deal with the team in March, and Morillo is set to make his Major League debut after eight pro seasons.
Jameson last pitched in a big league game on July 6, 2023, as he underwent a Tommy John surgery that September that cost him the entirety of the 2024 campaign. The 34th overall pick of the 2019 draft had posted a 2.63 ERA over 65 innings during the 2022-23 seasons, starting seven of 19 games but pitching mostly in a relief role as the 2023 season developed prior to his UCL injury. The righty has worked exclusively out of the pen at Triple-A this season, and he has a 2.70 ERA over 6 2/3 innings in Reno while recording 11 strikeouts against zero walks.
Now that he’s back in good health, Jameson can resume his career and perhaps carve out a firm place for himself within Arizona’s bullpen. He showed quite a bit of promise as a multi-inning reliever, as his past history as a starter gave him some extra durability coming out of the pen. The D’Backs could look to deploy Jameson as a long man or a swingman, at least letting him get some innings under his belt before perhaps trying him for higher-leverage work.
The 26-year-old Morillo spent his entire career in the Dodgers organization before joining the D’Backs as a minor league free agent back in November. Making his Triple-A debut this season, Morillo has thrown 6 1/3 innings of 1.42 ERA ball in Reno, with a 29.6% strikeout rate, 7.4% walk rate, and a huge 68.8% grounder rate to boot. The latter number stands out even amidst Morillo’s history as a groundball pitcher, and the solid walk rate is also noteworthy given his control problems earlier in his minor league career.
Between his high velocity, strikeout potential, and ability to keep the ball on the ground, there’s plenty to like about Morillo if he can find the consistency that has eluded him for a good chunk of his minors career. He’ll get a chance to show what he can do against MLB hitters during what might be a cup of coffee in the big leagues, depending on how Arizona chooses to align its bullpen beyond just this weekend.
Feyereisen has a 2.95 ERA over his 100 2/3 career innings in the majors, which covers parts of four seasons with the Brewers, Rays, and Dodgers from 2020-24. Feyereisen had solid numbers in 2021 and looked to be breaking out as a high-leverage reliever in Tampa’s bullpen in 2022 before a shoulder injury resulted in surgery that cost him the entire 2023 season.
Resurfacing in L.A. last year, he had an 8.18 ERA in 11 innings at the big league level, as Feyereisen clearly still had some rust from his long layoff. His 0.96 ERA in 9 1/3 innings in Reno this season is much more promising, and it was enough to give Feyereisen a shot with another NL West team as he looks to finally establish himself for steady bullpen work.
Kessinger played all over the infield in a backup capacity with the Astros during the 2023-24 seasons, appearing in 48 total games and hitting .131/.243/.213 in 70 plate appearances. His career Triple-A slash line of .268/.370/.401 is much more impressive on paper, if undermined by the fact that those seemingly solid numbers are barely average in the hitter-friendly Pacific Coast League.
The Diamondbacks acquired Kessinger in a trade in January but he hadn’t yet seen any action on Arizona’s big league roster, and his tenure with the organization might already be over if he is claimed on waivers or traded. Kessinger’s trade to Arizona in fact came after the Astros designated him for assignment previously, so history could repeat itself if another infield-needy team comes calling. If Kessinger clears waivers and is outrighted off the 40-man roster, he must accept the assignment since he doesn’t have the MLB service time or a past outright that would allow him to opt into free agency.
