What Does Zach Davies' Return Mean for D-backs Rotation?

The Diamondbacks have reportedly re-signed Zach Davies to a one-year deal to help bolster their rotation depth. While the team was not overly aggressive in pursuing starting pitching this off-season, they opted to have more stability by adding a veteran than trusting their stable of young arms to handle two rotation spots instead of one. 

Davies is coming off a decent 2022 season in which he provided league-average run prevention with a 4.09 ERA, or a 100 ERA+ in 134.1 innings. Advanced metrics aren't as bullish about his run prevention skills, as his 4.83 FIP, 4.57 xFIP, and 4.56 xERA were each half a run worse than his ERA. That likely suggests Davies is due for some ERA regression in 2023, especially when there may be an improvement in the offensive environment across baseball due to rule changes on shifts. The hope is he can lock down a third rotation spot for one more season and take the pressure off the team's top pitching prospects to perform out of the gate.

The immediate impact on the rotation means there is one less spot for the young arms to compete over next spring. Zac Gallen, Merrill Kelly, Madison Bumgarner, and Davies project to get four of the five spots in the Opening Day rotation, with only one spot up for grabs. Tommy Henry, Drey Jameson, Ryne Nelson, and Brandon Pfaadt will likely be competing for that one spot. Each of the four pitchers have a strong case to earn a rotation spot, whether it's past big league experience or a strong minor league track record. There is extra incentive for Pfaadt to get opportunities as a likely Top 100 prospect, as a first place finish in the 2023 National League Rookie of the Year race could possibly earn Arizona an additional first round pick. 

Alternatively the team could be creative in getting their young arms opportunities to pitch in the big leagues. The D-backs could look to potentially place one or two of their young arms in the bullpen, initially in a long relief role, in order for them to continue to get reps in the big leagues. Then as the roster needs change, they can either be stretched out into a starting role or move to a more important role in the bullpen. An example of each scenario is Wade Miley in 2012 and Archie Bradley in 2017. Both were pitchers who barely made the roster that year, but pitched well enough to earn better opportunities in the rotation and bullpen respectively. 

The addition of Davies in the rotation also applies pressure on Bumgarner to perform well at the beginning of the season. Arizona has the initial depth to replace the 33-year-old lefty should he prove to be incapable of the job, so he'll be on a short leash despite the team still owing him $37 million left over the final two years of his contract. After brutally struggling for the final four months of the season, save for a solid start here or there, he'll need to pitch well out of the gates for both his sanity and the team's benefit.

Looking at their rotation options for next spring, the D-backs have potentially up to eight pitchers they could turn to at the start of the season. As the year progresses, injuries may lower the number of pitchers available over the first half of the season. In the second half, especially as the team closes in towards the end of the season, the organization has potentially three more starting pitcher candidates to look at. Blake Walston, Slade Cecconi, and Bryce Jarvis are all eligible for the Rule 5 Draft next winter and the organization may want to promote them ahead of time instead of having to deal with a potential roster crunch.