Looking at the Diamondbacks rotation after the Madison Bumgarner signing

The Diamondbacks made a surprise move, adding former long time Giants pitcher Madison Bumgarner to a 5-year, $85M contract. The contract makes him the highest paid pitcher in the starting rotation, with Robbie Ray coming in second with an estimated Arb 3 salary of $10.8M. The team also has a pair of league-average innings eaters in Mike Leake and Merrill Kelly at the bottom of the rotation in addition to high-upside young arms in Luke Weaver and Zac Gallen. If the season were to start tomorrow, the starting rotation in my opinion would look like this:

1. Madison Bumgarner (Opening Day starter)
2. Zac Gallen
3. Robbie Ray
4. Merrill Kelly
5. Luke Weaver (innings limit)
6. Mike Leake (they’ll still use a 5-pitcher rotation but Leake will likely get a normal workload anyway)

The Bumgarner signing not only gives the Diamondbacks a reliable #3 starter in their rotation with playoff experience, but also simultaneously improves the trade market for Ray. The Dbacks shopped Ray at the deadline, with the Yankees balking at the Dbacks price for Ray and a deal never happening. Ray has been a mostly reliable starter for the Dbacks, averaging 28 starts and 150 innings a year since the team acquired him after the 2014 season. Ray misses a lot of bats, but walks are an issue and his fastball velo has been declining the past two seasons. Overall a pitcher with a track record of being mostly durable with a clean arm history along with above-average run prevention and average length of starts still has value across the league for a team looking to add a #3/4 LHP to their rotation. I expect the Dbacks to aggressively shop Ray in the offseason and take best offer.

The team has plenty of possible arms in addition to the six names mentioned in the opening paragraph with Alex Young, Jon Duplantier, Taylor Clarke, and Taylor Widener as other starting pitcher options on the 40-man roster. Young, Clarke, and Duplantier have experience pitching in a reliever role in their relatively brief careers. Of that group, Young was the most effective in 2019 which included winning the top performance of the season and the most unsung hero award on the Snake Pit. Young is a candidate for regression based on FIP and xFIP numbers (110 FIP- and 105 xFIP-), but batted ball data (48% GB rate and .316 xwOBA) and swinging strike (12.1%) rates suggest that the team should continue to give him opportunities in some capacity.

While the team lacks that #1 pitcher that will help carry the team through a potential postseason run, the team has enough upside and depth to stay in the race through the end of September. It’s unlikely the team will be able to go out and grab that type of pitcher seeing that Gerrit Cole and Stephen Strasburg banked $324M and $245M this free agency, so they’ll need either Gallen or Weaver to step up into that role if they want to make a run this decade.