2020 Arizona Diamondbacks Reviews #32: Luke Weaver

• rating: 3.83
• age: 27
• 2020 stats: 1-9, 12 GS, 6.58 ERA, 1.59 WHIP, negative 0.2 bWAR, positive 0.5 fWAR
• 2020 salary: League Minimum (Pre-Arb)
• 2021 status: In the Diamondback rotation

2020 Review

His recovery was demonstrated. Non-surgical rehab of his 2019 strain of his UCL was successful and in 2020 it was not reinjured. Prior to the 2020 season, he made mechanical tweaks to his delivery to keep his arm healthy. “We want to see his career thrive, not just his 2020 thrive. So we’re going to be mindful of it [Luke Weaver’s workload].” — Mike Hazen. Instead of shutting him down toward the end of the season, Hazen’s intentions were to add a sixth starter or build in extra rest for Weaver. He ended the COVID shortened season with 968 pitches.

“Those [previous setbacks] are all things that add up and get you to the next level.” — Torey Lovullo

His preparation was outstanding. He continuously improves his pitches (his curveball and cutter prior to 2019, and his 4-seam fastball in 2020). He fully completes his preparation and masters the little details. His approach has a positive impact.

The stuff looks good. The composure looks right. He’s going about it the right way. He’s coming in here and getting all the work done and doing all the little things right. — Mike Matheny, February, 2016

“Credit to him [Luke Weaver] coming in as ready as he did.” — Torey Lovullo, July 2020

“We know he had a great offseason and put himself in a good position physically.” — Mike Hazen, 2020

His 2020 ERA understated his true pitching skill. Of the 8 starting pitchers for the Diamondbacks, only Robbie Ray had a higher ERA. It’s fair to say his ERA was an anomaly because Luke Weaver’s FIP ranked third. Let’s look at four reasons why his ERA will improve next season.

• Factors largely out of his control (BABIP, % runners left on base, and Homers per fly ball) worked against him in 2020. Next season, they will tend to return to league averages, improving his ERA. An article with a calculation of projected ERA is here.
• “You can still throw a good curveball at 60 percent spin efficiency.” — Luke Weaver. He made his curve better than good. Prior to the 2019 season, he improved his curveball with a better grip and ‘less flick and more drive’ with his wrist. Details are in this article. Batting average against it improved from .329 to .286, while slugging against it improved from .589 to .381. Because his curve results regressed in 2020, more tweaks could improve results next season.
• Statistics suggest he improved his cutter prior to the 2019 season. The cutter’s whiff percent increased from 4% to 12% in 2019. In 2019 and 2020, he increased its’ frequency from 5% to 12-13%. His cutter is unique. In March 2019, Jack Sommers called it a ‘slider/cutter combo.’
• In September he improved his 4-seam fastball and increased its frequency (from 47% in August to 61% in September). In 2020, it’s spin (average of 2467 rpm) ranked 86th percentile in the Majors. His 4-seam fastball’s 26.2 Bauer Units ranked fourth of the eight Diamondback starters, and it was significantly above the league’s 4-seam fastball average of 24.7 Bauer Units. High Bauer Units suggest his 4-seam fastball has a lot of movement. It’s above-average movement was confirmed in the following:

“By being more efficient with his spin — something the Diamondbacks are elite at teaching — he finally has above-average ride, and that plays up because of the low release point on his drop-and-drive delivery. Now his fastball is getting more whiffs than it has since his rookie year, and he’s pairing it with the most right-on-right changeups of his life.” — Eno Sarris, August 2020

Data from Baseball Reference, FanGraphs, Brooks Baseball, and Baseball Savant.

2021 Preview

He will be in the rotation. Let’s look at how he ranked among the seven Diamondback starters in 2020 who will return in 2021. The seven returning starters are Madison Bumgarner, Zac Gallen, Merrill Kelly, Caleb Smith, Taylor Clarke, Alex Young, and Luke Weaver.

• He ranked #1 with projected ERA of 2.71 (article).
• He ranked #3 with FIP of 4.67 in 2020.
• He ranked #4 with projected ERA of 4.65 (FanGraphs —Steamer only).
• He ranked #4 with 26.2 Bauer Units for his 4-seam fastball in 2020.

With continuously improved pitches and thorough preparation, he is ready for success in 2021. More specifically, we considered four reasons to expect that he will enjoy more success in 2021. Will he will pitch at the ace level with an ERA less than 3.00? Perhaps I’ll joyously write about foresight when it happens.

“I feel like it’s going to be a huge year for me because now I feel like I have four pitches that I can definitely throw.” — Luke Weaver. His words apply to 2021 as much as they did to 2019.