The Diamondbacks' Rotation Is a Liability, And It Could Derail the Season
While the Diamondbacks are still in the hunt for a postseason spot, their current rotation could sink their season.
After 80 games, the Arizona Diamondbacks currently sit at 41-39. While their roster is battered after an unprecedented amount of injuries, they remain just three games out of a playoff spot. They’re in a position that if everything clicks on all cylinders in the second half of their season, they could make a run at a Wild Card spot. That’s exactly the situation they were in just 12 months ago and fell short via tiebreaker.
However, one key area could very much undermine their efforts to the point where this run never gets off the ground. That area is their current starting rotation.
What was once considered the team’s strongest and deepest section of their roster has turned into a major liability. Much of their depth has been thinned out due to injuries, and not the kind that teams want to deal with. They lost four starting pitchers to Tommy John surgery (Corbin Burnes, Jordan Montgomery, Blake Walston, and Tommy Henry). As of June 27th, they only have six healthy starters on their 40-man roster.
Without making a move at the trade deadline, and barring more injuries, this is the starting five that the Diamondbacks will have for the rest of the season: Zac Gallen, Merrill Kelly, Ryne Nelson, Eduardo Rodríguez, and Brandon Pfaadt.
Here’s how the current starting five stacks up to the rest of the league, in quality start rate and average Game Score.
Team Metrics: 79G (69 GS), 4.10 ERA/4.34 FIP, 92 ERA+, 34.8 QS%, 49.4 GmScA
MLB Average (thru 6/25): 2408 GS, 4.05 ERA/4.11 FIP, 100 ERA+, 36.3 QS%, 52 GmScA
At first glance, the Diamondbacks’ current rotation is slightly underperforming the league averages. However, that’s not what they paid for, and the expectation was the rotation was going to be the backbone of the team.
When looking at each pitcher, it’s pretty clear that Kelly is carrying the rotation. Ryne Nelson has delivered some solid starts as well, even though his length has been shortened due to spending most of the year in the bullpen. But what’s clear is that Gallen, Rodríguez, and Pfaadt have not performed to expectations, as all three have an ERA north of 5.00 and ERA+ under 80.
The most frustrating part about this is that those are the team’s three highest-paid pitchers. Arizona has invested $138.5 million between Rodríguez ($80M), Pfaadt ($45M), and Gallen ($13.5M). To say they’ve gotten a poor return on investment is an understatement.
Rodríguez can point to an injury that knocked him out for three turns in the rotation, and his FIP (4.08) outperforms his ERA (5.40) by more than a full run. The rest don’t have much of an excuse.
I’ve already put together a medium-deep dive (as much as Substack would allow) on Gallen’s struggles, which is worth checking out instead of repeating here.
Without the improvement of Gallen, Rodríguez, and Pfaadt, this team’s postseason chances are dead on arrival. They simply cannot afford to have a liability in 60% of their remaining games, even with a high-performing offense.