The Diamondbacks are moving right-handed starter Luke Weaver to a bullpen role to begin the season and will open the year with lefty Caleb Smith in the rotation in his place, manager Torey Lovullo announced to reporters Tuesday (Twitter links via Steve Gilbert of MLB.com and Nick Piecoro of the Arizona Republic). Arizona’s rotation to begin the season will be Madison Bumgarner, Merrill Kelly, Zach Davies, Smith and Zac Gallen.
Weaver, 28, has been used exclusively out of the rotation since coming over from the Cardinals alongside Carson Kelly, Andy Young and a Competitive Balance Draft selection in the trade that sent Paul Goldschmidt to St. Louis. As was the case in his short time with the Cardinals, who originally drafted him with the 27th overall pick back in 2014, Weaver has at times looked like a quality big league rotation piece but has struggled to stay healthy.
The only season in which Weaver has managed a full workload for the Diamondbacks was the shortened 2020 campaign, when he was rocked for an uncharacteristic 6.58 ERA in 52 innings over the life of 12 starts. Weaver posted a 2.94 ERA with brilliant strikeout and walk rates through a dozen starts in 2019, his first year with the Snakes, but also spent the bulk of the season on the injured list due to a forearm strain. In 2021, he turned in a solid 4.25 ERA with slightly worse (but still solid) strikeout and walk rates. A shoulder strain, however, kept him out from mid-May until September 1.
It’s of course possible that it’ll prove to be a short-term move to the bullpen for Weaver, but it’ll also be interesting to see whether a move to shorter stints will help him to remain healthy. Weaver’s fastball sat at an average of 93.7 mph last year while working as a starter, and it’s common for pitchers to see their velocity tick upward when moving to a relief role. Weaver also has fairly extreme splits when facing lineups for the second and third time in a game. When facing the lineup the first time through, he’s held opponents to a rather tepid .241/.297/.393 output.
As for the 30-year-old Smith, he’s no stranger to a rotation role. He pitched exclusively as a starter with the Marlins in 2018-19 and made 13 starts for Arizona last year, though the D-backs deployed him more heavily out of the bullpen in 2021. Smith has had more success pitching in relief in his career, with superior marks in ERA (3.45 to 4.90), walk rate (9.8% to 11.3%) and home run rate (1.15 per nine to 1.79 per nine) relative to his work as a starter. That said, Smith did pitch to a 4.41 ERA with a 26.3% strikeout rate and 9.6% walk rate in 230 2/3 innings as a member of the Marlins’ rotation in 2018-19.
Both Smith and Weaver have four-plus years of Major League service time and are thus controlled through the 2023 season. Given their relatively short amount of remaining club control, there could be trade speculation surrounding both this summer as the trade deadline approaches. However, Arizona recently extended two of its most popular trade candidates — Ketel Marte, Merrill Kelly — continuing to make an effort to put a competitive roster on the field as they await a wave of high-end prospects who are on the cusp of MLB readiness.