Joe Mantiply

The Diamondbacks entered the offseason in search of a new first baseman, a closer and some right-handed thump in the lineup, among other items on the to-do list. They’ve broadly succeeded, acquiring Josh Naylor from the Guardians to replace free agent Christian Walker and re-signing Randal Grichuk. The Snakes haven’t found a slam-dunk closer, but they signed a new (co) ace, shocking the industry with their signing of Corbin Burnes for six years and $210MM.

While there’s still one marquee free agent reliever on the market — David Robertson has yet to sign — it appears increasingly likely that the Diamondbacks will largely go with the arms who are already in camp as they look to sort out the ninth inning. Arizona’s payroll is already projected for a franchise-record $195MM. That’s a new highwater mark by a measure of nearly $30MM. We can always adopt the “never say never” mentality as long as there are a few viable closing options on the free agent and trade markets, but the D-backs may already have their closer in house. At present, A.J. Puk and Justin Martinez appear to be the front-runners.

Puk, acquired at the deadline from the Marlins in exchange for young slugger Deyvison De Los Santos and outfielder Andrew Pintar, enjoyed a quietly dominant season in 2024. His cumulative 3.15 ERA looks more good than great, but it’s skewed by a failed experiment wherein the Marlins tried to stretch him back out as a starter early in the season. Puk was clobbered for 17 runs in 13 2/3 innings. He moved back to the bullpen, and from that point forth was arguably the best reliever in the sport.

After giving up 17 earned runs in his four starts, Puk only allowed 11 more earned runs for the entire season. He posted a 1.72 ERA out of the bullpen in 2024, fanning a colossal 35% of his opponents against a terrific 5.1% walk rate. Opponents averaged only 86.6 mph off the bat against him in that time with a middling 32.6% hard-hit rate. Per Statcast, only five of his opponents’ batted balls in that time were barreled. Puk allowed a run in his second appearance with the D-backs and then went on a run for the ages, rattling off 23 2/3 scoreless innings with a 38-to-4 K/BB ratio. He punched out 44.7% of opponents in that career-best run.

Martinez was nearly as dominant for the early portion of the 2024 season. The young flamethrower posted a 1.60 ERA with a 27.5% strikeout rate and mammoth 64.5% grounder rate in his first 50 innings of work. His exit velocity and hard-hit rate were nearly identical to Puk’s marks as a reliever. An 11.5% walk rate was in clear need of improvement, but for a 22-year-old who averaged better than 100 mph on both his four-seamer and sinker, it’s hard to draw up a more promising start.

That run of dominance didn’t last the full season, however. While Martinez remained a solid reliever, his 3.90 ERA over the final 27 2/3 innings of his season was far less eye-catching. The young righty’s strikeout rate actually ticked up during that span, perhaps due to roughly doubling the usage of his four-seamer at the expense of his sinker, but his grounder rate fell sharply. There was surely some poor fortune in play, as Martinez was hampered by a .388 BABIP during this stretch despite continuing to limit hard contact (and allowing only one home run).

Whether in the ninth inning or working in a setup capacity, both Puk and Martinez will be in high-leverage roles this season. They were two of the D-backs’ top five arms in terms of their average leverage index — but not the top two. Paul Sewald‘s departure in free agency subtracted one of Arizona’s top leverage arms, but it was actually righty Ryan Thompson who found himself most frequently in high-leverage spots, followed by Martinez and then by fellow righty Kevin Ginkel.

The 32-year-old Thompson isn’t the prototypical power arm often associated with pressure-packed, late-inning situations. He’s a sidearming righty who averages just 91 mph on his sinker and 92.5 mph on his lesser-used four-seamer. Thompson’s 19.1% strikeout rate was well below the 23.4% league average among relievers. However, he boasts a 61% grounder rate, rarely issues walks (5.5%) and posted nearly identical results versus righties (.254/.299/.377) and lefties (.254/.293/.377). He picked up two saves and 24 holds.

Ginkel, 30, has quietly emerged as a key arm in Phoenix. He was never a top prospect and didn’t truly establish himself as a reliable reliever until his age-28 season, in 2022. Over the past three seasons, he’s tossed 164 2/3 innings with a 2.95 ERA. It’s not necessarily flashy, as Ginkel is more good-than-great in terms of strikeout rate (26.5%), walk rate (7.3%), swinging-strike rate (12.5%), ground-ball rate (47.1%) and fastball velocity (96 mph average) in that time. Even with the lack of one standout area in which he truly excels, his above-average rates across the board have made him a consistent and reliable late-inning option for manager Torey Lovullo.

Also entering the mix is 34-year-old Kendall Graveman, who signed a one-year, $1.35MM deal after missing the 2024 season due to shoulder surgery. With 24 saves and 56 holds from 2020-23, Graveman is no stranger to late-inning work. After moving to the bullpen in Sept. 2020 with the Mariners, Graveman rattled off 197 1/3 innings with a 2.78 ERA, 24% strikeout rate, 10.3% walk rate and 49.2% grounder rate. At his best, Graveman averaged better than 96 mph on his heater and offered a Ginkel-esque blend of above-average strikeout, walk and ground-ball rates while sitting around 96 mph with his main offering. Whether he can return to that form in the wake of last year’s shoulder surgery is an open question.

However it shakes out, the Snakes look to have a solid quintet of arms rounding out the late-inning group at Chase Field. Lefty Joe Mantiply offers a solid middle-inning complement who has picked up around 12 holds per year over the past four seasons. A starter who doesn’t make the rotation (e.g. Jordan Montgomery, Ryne Nelson) could hold down another spot. Bryce Jarvis, Kyle Nelson and non-roster candidates like Shelby Miller, Scott McGough, John Curtiss and Josh Winder (among others) will vie for what’s likely one open spot.

There’s enough left on both the trade and free agent markets that it’s not impossible to envision a change still impacting Lovullo’s bullpen composition. Signing Robertson might be too pricey, likely pushing the D-backs into $200MM+ payroll territory for the first time, but if GM Mike Hazen ultimately finds a trade partner for Montgomery, any savings could make Robertson feel likelier. The Padres have been open to offers on Robert Suarez. Trading within the division probably isn’t either team’s first choice, though. A Ryan Helsley trade before next offseason feels virtually inevitable but also seems likelier to happen in-season at this point.

In any bullpen, there’s almost always room for one more addition. But, if this is the group the D-backs take into the season, they can still feel good about an impressive breadth of experienced late-inning arms who have the makings of a strong overall unit.