The 2021 Arizona Diamondbacks will enter the season with what I will call a virtual copy and paste of the same rotation that they finished last season with. This time around, the 2021 Arizona Diamondbacks will look for much better results than the combined rotation ERA of 5.04 and FIP and an xFIP both near 5.00.
The projected rotation for the 2021 Arizona Diamondbacks will loo as followed come opening day barring any major changes:
2021 Arizona Diamondbacks: A Floor And A Ceiling
The Diamondbacks rotation last year was awful to say the least. The Madison Bumgarner signing initially looked like a big boost, but the 2020 numbers didn’t prove that by any means.
Despite the disappointment in 2020, this 2021 Arizona Diamondbacks rotation has plenty of potentials. Can they be a top-five rotation? No. Top 10? Probably not, but this rotation has the upside to be a middle of the pack rotation and people shouldn’t just expect this rotation to be as bad as it was in 2020.
Starting with the obvious number one for the 2021 Arizona Diamondbacks is Zac Gallen.
|2019 (As a Diamondback)||2.89||3.65||3.89|
Since joining the Diamondbacks midway through 2019, Gallen has improved upon his control. Gallen has decreased his BB/9 since joining the Diamondbacks down from the 4.46 walks per nine innings as a Marlin (Yes, small sample size, only 36 innings). That number dropped to 3.71 in his 43 innings in Arizona in 2019. In 2020, he lowered the number again down to 3.13 walks per nine innings.
A part of Gallen’s game that shines is his ability to produce a career 28.5% strikeout rate, suitable for a K/9 of 10.54 in his short career. His ability to draw swing and misses ranked him in the 75th percentile in 2019 and 2020. Even if his strikeout rate plateaus where it is now, It won’t have much of an effect on his long term upside as a possible top of the rotation arm.
The 2021 Arizona Diamondbacks will look for a bounce back from last off seasons “big fish”. Bumgarner in 2020 was disappointing, to say the least. Coming into 2020, before a game was even played, Bumgarner was down three mph on his pitches, and that showed to be a massive blow to his game.
In 2020 Bumgarner pitched in 41.2 innings over nine starts for the Diamondbacks. Bumgarner had an uninspiring 6.48 ERA with a FIP of 7.18, and xFIP of 5.85. In 2020, Bumgarner set a career-low strikeout rate at 15.8% with a K/9 of 6.48, his lowest since 2010.
Much of the inflated ERA numbers will come from his 2.81 home runs allowed per nine innings last season; that number is double the 1.38 HR/9 set in 2017. Bumgarner’s HR/FB (home run/fly ball ratio) was evidence of his decreased velocity; his HR/FB ratio rose 9.4% from the previous year and might not entirely be where it was if the velocity doesn’t come back even just a few ticks. The 2021 Arizona Diamondbacks will look for the lefty hurler to come close to form and be a solid innings-eater for the team.
Entering his first full season in the desert, Caleb Smith offers a profile similar to Robbie Ray‘s likes. In his time as a Miami Marlin, Smith showed off intriguing strikeout abilities while operating as a heavy fly ball pitcher.
The biggest hole in his game is arguably the high fly ball rates and the quality of the batted balls he is giving up. Caleb Smith has a career 51.8% fly-ball rate and a career 14% HR/FB rate in his career.
The 2021 Arizona Diamondbacks will look to help smith re-discover the form he was in during his impressive 2018 campaign. In 2018, Smith threw only 77.1 innings over 17 starts. In that half-season sample size, Smith had an impressive 27% strikeout rate to go with a 4.19 ERA and a 3.96 FIP.
Luke Weaver was an interesting player to monitor from the Paul Goldschmidt blockbuster deal. In his first season in the Diamondbacks organization, Weaver would be shut down midway through the year that would ultimately end his year.
Prior to the shutdown, Weaver was looking like a huge gain for the Arizona Diamondbacks. In 64.1 innings over 12 starts, Weaver held an impressive 2.91 ERA along with a FIP of 3.07 and an xFIP of 3.89. In those innings, Weaver had an impressive 5.4% walk rate compared to his 26.5% strikeout rate.
The 2020 season for Weaver like a lot of players was an utter disaster. Weaver would throw 52 innings in 12 starts and would post a 6.58 ERA to go with having a FIP/xFIP north of 4.50.
Weaver will enter the 2021 Arizona Diamondbacks season looking to improve upon his control. In 2020 Weavers walk percentage increased slightly, up to 7.6% from 5.4%. Weaver had a .362 wOBA last season, and compared to his xwOBA of .316, which isn’t too great of a number either, Weaver looks like a decent bounce-back candidate given the unluckiness of home-runs allowed last season.
Merrill Kelly isn’t going to blow you away; he is who he is. Since returning to MLB after a brief stay in the KBO, Kelly has put together two quality seasons in the desert. In his two seasons in Arizona, Kelly has shown the ability to be a solid back end of the rotation starter.
Kelly has a major lack of drawing swing and miss from opponents. Merrill Kelly is a pitch to contact pitcher and in 2020 lowered his walk percentage from 7.3% down to just 4% in 2020 that would rank him in the 95th percentile among qualified pitchers.
Merrill Kelly will look to be the 2021 Arizona Diamondbacks fifth starter, but if injuries or if the wheels all fall off. The Diamondbacks could look to other names to fill in holes or for spot starts. This Diamondbacks rotation is by no means amazing, but this rotation has the ability to be a middle of the pack rotation.
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Main image credit: Embed from Getty Images