Snake-Bitten: What’s Wrong With the Diamondbacks Rotation?

Snake-Bitten: What’s Wrong With the Diamondbacks Rotation?

Written By: Connelly Doan
Follow him on Twitter: @ConnellyDoan
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The Arizona Diamondbacks had a rotation to get excited about coming into the 2020 season. They had the strikeout stuff of Robbie Ray, an exciting prospect in Zac Gallen, the return of a healthy Luke Weaver (who was excellent prior to his 2019 injury), and the big signing of ace Madison Bumgarner. We are now roughly 30% through the regular season and things have not gone as planned for the Dbacks’ rotation. The team is 8-11 and the rotation’s best performers have been Merrill Kelly and Gallen.

On the other hand, the team’s top-three starters (Bumgarner, Ray, and Weaver) have a 9.35 ERA, 10.59 ERA, and 11.85 ERA, respectively. These performances go beyond the explanation of the season being young and arms still needing to get loose.

I will be taking a closer look at each of these three pitchers to get a better idea of why things have been going wrong for them and whether or not better results can be expected.

Madison Bumgarner

Bumgarner was one of the bigger free-agent signings this offseason, inking a five-year, $85 million contract with the Diamondbacks. As such, his 0-3 start to the season and overall performance is probably the most disappointing of the three pitchers. His 9.35 ERA and 1.56 WHIP are astronomically high compared to his 3.19 and 1.11 career marks, his 8.4% walk rate is the highest of his career, and his 15.7% strikeout rate is the lowest of his career. It was well-recognized that MadBum could experience a relative decrease in performance by leaving pitcher-friendly Oracle Park, but nothing like this was expected.


The three main things to consider here are Bumgarner’s velocity, his health (which impacts his velocity in part), and his pitch location. Bumgarner’s 2019 fastball velocity (91.4 MPH) was closer to what he had been hitting prior to his string of injuries, and his added spin (2,405 revolutions per minute) was a further benefit. However, his fastball is averaging just 87.8 MPH this season and while his fastball spin rate (2,387 revolutions per minute) is in the 86th percentile in baseball, it is still much lower than last season.


The logical place to turn in the face of such decreased velocity is his health. 2019 was Bumgarner’s first healthy season since 2016 and he was able to pitch 207 ⅔ innings. As such, there was no thought that things would be different for 2020. However, manager Torey Lovullo said in a press conference after Bumgarner’s August 9 start that he was removed from the game after experiencing back spasms. The team then placed him on the 10-day IL the next day. Nothing was mentioned about Bumgarner experiencing these spasms before, but he is notorious for his “tough guy” attitude, so it wouldn’t be surprising if he had not felt 100% in his previous starts but pitched through it.

Pitch Location

Finally, Bumgarner’s pitch location has been dreadful this season. His fastball and cutter have been left in the middle of the plate and upper half of the zone, which won’t work with diminished velocity. Consequently, his batted-ball profile has suffered; his 91-MPH average exit velocity is the highest it has been since Statcast began recording the stat and his 21.6-degree launch angle has led to seven allowed home runs over his first four starts.

All in all, things have looked significantly off for Bumgarner. Hopefully, the time on the IL will help him get to 100%, or at least much closer to it than he has been.

Robbie Ray

Robbie Ray has always profiled as a pitcher with huge strikeout upside thanks to a lively fastball and a devastating slider/curveball combination who can never quite get his command under control. His walk rate and ERA have always suffered a bit, but his strikeout abilities have kept him as a higher-end starter.

That general profile remains the same this season, but the negative aspects of his game have been hugely magnified. Ray has a 10.59 ERA, a 26.4% strikeout rate, and a 16.1% walk rate through his first four starts. Can he turn things around and pitch at the caliber he has shown before or will this season continue to be his worst?

Pitch Arsenal

Unlike Bumgarner, Ray’s pitch arsenal looks as good, if not better than it has in previous seasons. Ray has seen an increase in both velocity and spin rate on all three of his main pitches compared to last season: fastball (94.3 MPH vs 92.4 MPH in 2019; 2,503 rotations per minute vs 2,257 in 2019), slider (86.3 MPH vs 84.2 MPH in 2019; 2,410 rotations per minute vs 2,145 in 2019), curveball (83.5 MPH vs 81.6 MPH in 2019; 2,329 rotations per minute vs 2,045 in 2019). His overall swinging-strike rate is currently lower than it was in 2019 (11.4% vs 13.6% in 2019), but it is still at a respectable mark.

This is an encouraging sign in that Ray’s “stuff” still seems good outside of a game context. Watching the highlights of his last start, it is apparent that he can still strike hitters out and that he has gotten unlucky on balls in play (his .349 BABIP vs a career .313 mark supports this as well).

Pitch Command

While Ray’s pitch arsenal may look good on paper, the fact is that it doesn’t matter how good his pitches are if he cannot locate them. His fastball is up when it does find the zone, his curveball is being left in the middle of the plate, and his slider is all over the place. Ray has always had command issues, but they have never been this bad.

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Ray’s increased lack of command could be just one mechanical tweak or mental hurdle away from rectifying itself. Given his strikeout numbers and his BABIP, I feel that Ray has a good chance of seeing some positive regression over the course of the season. However, making small changes in baseball is difficult, which is what Ray will need to do to get back to normal.

Luke Weaver

I was excited about Luke Weaver heading into the 2020 season, naming him as my breakout player for the Diamondbacks. He pitched extremely well prior to his forearm/elbow injury, so there was optimism that he would pick up where he left off for 2020.

Unfortunately, he has done the exact opposite. He has averaged just over 3 innings per start and has a career-high 10% walk rate. Is there still a chance that Weaver can return to his 2019 form?

Fastball Location

The first thing to note is Weaver’s inability to stay out of the middle of the plate with his fastball and inability to find the plate with his cutter. His fastball has shown more velocity (94.4 MPH vs 93.8 MPH in 2019) and more spin/movement (2,412 revolutions per minute vs 2,308 in 2019) than last season, which is a good sign.

However, his location has not been good, leading to a .360 batting average against the pitch. There is a change that he has gotten unlucky on balls in play; his overall BABIP of .395 is much higher than his career mark of .327. That being said, Weaver will have to use his fastballs more effectively if he wants to be competitive.

Changeup Profile

The other thing to consider with Weaver is his changeup. The changeup has always been Weaver’s secondary pitch and it was a fantastic option for him in 2019. His 2019 changeup was thrown at 84.5 MPH with little horizontal movement (2.6 inches less than league average) and some vertical drop (0.1 inches greater than league average). Weaver had an impressive 18.3% swinging-strike rate with the pitch and a .169 batting average against.

2020’s changeup has profiled differently; Weaver is throwing the pitch a bit harder (85.3 MPH) with more horizontal movement (1.5 inches greater than league average) and much less vertical drop (4.5 inches less than league average). His batting average against the pitch is up (.250), but so is his swinging-strike rate (20.8%), so the pitch has still been effective.

Overall, I think Weaver can salvage his season if he can better-locate his fastball and cutter. However, he will need to be given more opportunities to start to make that correction. While nothing has been said in terms of replacing him in the rotation and the Diamondbacks are now down an arm in Bumgarner, it would not be surprising if Weaver started losing opportunities because of his performance.

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