The Diamondbacks have signed right-hander Isaiah Campbell to a minor league deal, according to his transactions tracker at MLB.com. The ACES client has been assigned to the Triple-A Reno Aces but will presumably receive an invite to big league camp in spring training.
Campbell, 28, has appeared in each of the past three big league seasons. Suiting up for the Mariners and Red Sox, the righty has thrown 43 innings in the majors, allowing 5.65 earned runs per nine. His 21.9% strikeout rate and 8.3% walk rate are close to average while his 47.7% grounder rate is a few ticks better than par. His .341 batting average on balls in play and 66.6% strand rate are both to the unfortunate side, so metrics like his 4.34 FIP and 3.89 SIERA are a bit more optimistic than his ERA.
Only 7 2/3 of those innings came in 2025, as he spent most of the season with Triple-A Worcester. He logged 57 2/3 at that level this year with a 3.90 ERA. His 18.1% strikeout was a bit on the low side but he got grounders on 50.5% of balls in play. He averages in the mid-90s with his four-seamer and sinker but throws his slider more than half the time. He added a curveball in 2025 and mixed that in sporadically.
Campbell exhausted his final option season this year and will be out of options going forward, which will make it harder for him to hold a roster spot. The Sox outrighted him off their 40-man in October and he was able to elect free agency.
The bullpen was a big problem for the Snakes in 2025. They had planned for A.J. Puk and Justin Martínez but both were felled by UCL surgeries and other guys dealt with injury problems as well. Their relief corps had a collective 4.82 ERA this past season, which was better than just the Angels, Rockies and Nationals.
They will surely make some more moves to upgrade their bullpen before Opening Day but Campbell gives them some extra non-roster depth for now. He has just over a year of MLB service time. If he can earn a roster spot and hold it, he can be cheaply retained beyond the 2026 season.
Photo courtesy of Bob DeChiara, Imagn Images