Diamondbacks Sign Merrill Kelly

The Diamondbacks officially announced a reunion with Merrill Kelly on a two-year contract with a 2028 vesting option. The Apex Baseball client is reportedly guaranteed $40MM. He receives a $2MM signing bonus and will make successive $17MM and $21MM salaries. If Kelly reaches 170 innings in 2027, he’ll lock in a $12MM salary for the 2028 season. If he reaches 185 innings in ’27, that ’28 guarantee will jump to $14MM. The D-Backs cleared a roster spot earlier by flipping Kyle Backhus to the Phillies.

The 37-year-old Kelly returns to the team with which he has spent nearly his entire major league career. Though initially drafted by the Rays in the eighth-round of the 2010 draft, Kelly made his big league debut with the Diamondbacks back in 2019 after a four-season stay in Korea as a member of the KBO’s SK Wyverns (now known as the SSG Landers). After a pedestrian rookie campaign in the majors where he pitched to a league-average ERA in 32 starts, Kelly managed to fashion a role for himself as one of the better mid-rotation arms in the majors.

Since the start of the 2022 campaign, Kelly has pitched to a 3.47 ERA in 108 starts. He’s struck out 23.1% of his opponents while walking 7.7% in that time, leaving him with a 3.81 FIP. Although a 4.03 SIERA and other so-so peripherals cast him as a step down from your prototypical front-end starter, the veteran has managed to remain a durable and productive rotation piece. Kelly particularly endeared himself to Arizona fans when he delivered a brilliant 2.25 ERA over 24 postseason innings during the club’s run to the World Series in 2023.

Amid a disappointing 2025 season where the Diamondbacks were ravaged by injuries to everyone from star closers Justin Martinez and A.J. Puk to newly-signed ace Corbin Burnes, the team engaged in a sell-off at trade deadline and shipped Kelly to the Rangers in exchange for a trio of pitching prospects. Kelly put up fairly pedestrian numbers across ten starts with the Rangers: a 4.23 ERA and near-matching 4.18 FIP across 55 1/3 innings of work.

Even while the veteran was in Texas, an offseason reunion with the Diamondbacks was already being speculated upon. Kelly spoke fondly of Arizona and expressed an openness to re-signing when asked about the possibility while the Rangers were visiting Chase Field in the season’s final few weeks. “Definite” interest in a reunion with Kelly was reported on Arizona’s side shortly before last week’s Winter Meetings, and now the sides have come together on a deal.

Turning to the deal itself, Kelly’s $40MM guarantee clocks in just ahead of the two years and $36MM MLBTR predicted for the right-hander when ranking him as the #25 free agent in this offseason’s Top 50 MLB Free Agents list. The Snakes were aggressive both in their offer and the timing of the deal; while the free agent market for position players and especially relievers has kicked into gear already, Kelly is just the third starting pitcher from MLBTR’s Top 50 to sign a contract this offseason. He joins Dylan Cease and Cody Ponce, both of whom received guarantees that slightly eclipsed MLBTR’s predictions.

Now that he’s set to return to Arizona, Kelly stands as the favorite to start for the Diamondbacks on Opening Day this year. He’ll join a rotation that already added Michael Soroka and will reunite with former teammates Eduardo Rodriguez, Brandon Pfaadt, and Ryne Nelson. Burnes could be a factor later in the season but is not expected to pitch until sometime in the second half after undergoing Tommy John surgery in June. While the team’s rotation certainly looks much more complete with Kelly back in the fold, bringing the right-hander back shouldn’t stop the team from pursuing other rotation additions after the club’s pitching staff finished 19th in the majors with a 4.29 ERA last year.

Of course, adding beyond this could prove to be easier said than done. The Diamondbacks are projected for a payroll just north of $171MM in 2026, according to RosterResource. That rises to north of $205MM for luxury tax purposes. GM Mike Hazen has suggested that, while Arizona’s payroll would likely be moving downward from its 2025 level, that would still leave the team with room to spend. The club spent $188MM on its payroll last season, however, meaning they currently sit less than $17MM from that mark.

Perhaps that leaves enough wiggle room to reunite with Paul Goldschmidt on an affordable one-year deal, a move the Diamondbacks have been said to be contemplating, but Kelly will surely go down as the team’s biggest expenditure unless an increase in payroll is approved or the team makes a trade that clears salary. To that latter point, the hot stove has been burning with Ketel Marte trade buzz in recent weeks. Moving Marte would certainly clear payroll off the books (and simultaneously add some young rotation options as part of the return), though Hazen has consistently downplayed the likelihood of a deal surrounding Marte actually coming together.

Ken Rosenthal of The Athletic first reported the Diamondbacks and Kelly were finalizing a two-year, $40MM deal. Nick Piecoro of The Arizona Republic reported the option specifics. David Brandt of The Associated Press had the salary structure.