Luke Weaver Changes It Up

Photo credit: USA Today Sports

Photo credit: USA Today Sports

ORIGINALLY PUBLISHED: BASEBALL PROSPECTUS

At the tail end of 2017, Luke Weaver made 10 starts for the Cardinals as a 23-year-old. The results signaled the imminence of a coming breakout. He mixed average velocity with exceptional command and threw a curveball showcasing some feel for spin. Hitters struggled to lift his key secondary pitch, a changeup that had a 91st percentile ground-ball rate, and it helped Weaver coast through 60 1/3 innings with a 3.88 ERA and 3.19 DRA.

Going into 2018, many thought Weaver would have an improved breaking ball, netting him three average-to-plus pitches with command. He worked diligentlyduring the 2018 offseason on his curveball, but come the regular season his work did not pay off. His curveball decreased in effectiveness and his bread-and-butter changeup bottomed out as well. He posted a 4.95 ERA and 4.62 DRA in 136 innings.

“You get timid and you don’t want to throw [the changeup] because you don’t want it to get hit,” Weaver told me recently. “But then sometimes you just gotta say screw it.”

St. Louis relegated Weaver to the bullpen for five of his final six appearances last season, as the right-hander had been unable to recapture the pitch that convinced many he could become an integral piece of the Cardinals’ long-term rotation. The team that drafted him 27th overall in 2014 proceeded to trade him to the Diamondbacks as part of the return for Paul Goldschmidt.

This offseason, following the early December trade, Weaver focused on his changeup. “It was a lot of time in the offseason grasping back to what made it good,” Weaver said. “What was I doing to get swings, to get less contact.”

Through six starts with his new club this season, Weaver sports a 3.73 ERA and 36/7 K/BB ratio in 31 1/3 innings, with the highest swinging-strike rate of his career. His pitch mix is different, and at times, the same, but his changeup is back and it’s part of a wider overhaul of his evolving repertoire.


Statistics back up Weaver’s desire to revert his changeup to its 2017 form. His velocity rose slightly across the board from 2017 to 2018, with his changeup doing the most gaining to 86 mph on average. In 2019, the pitch has fallen back to 85 mph, but his fastball velocity has stayed at 94 mph. As a result, the velocity differential between his fastball and changeup increased from 8.3 mph in 2018 to 9.2 mph in 2019, closer to the 10 mph difference often linked to a greater whiff rate. The pitch changed shape as well, losing fade or arm-side run from 2018 and gaining more vertical drop.

Credit: Brooks Baseball

Credit: Brooks Baseball

Weaver is back near the top quarter of the league with his changeup’s ground-ball rate. A combination of his newfound confidence with the pitch, the pitch’s altered shape, and the velocity differential have bumped its swinging-strike rate up to 20 percent, five percentage points higher than either of the last two seasons.

Weaver’s process for manipulating movement on his pitches starts with determining the different ways in which he can throw them and which pitches he feels most comfortable throwing, followed by analyzing what the break of each pitch does. The manipulation of his changeup’s movement highlights a broader alteration to how his pitches work in unison.

Take, for example, his approach to right-handed hitters. In 2018, he threw them 60 percent fastballs, 21 percent changeups, 12 percent curveballs, and eight percent cuttters. This season he’s backed up his changeup usage to righties and made his cutter the featured secondary pitch. That switch is not accidental, as Weaver’s cutter gained nearly one inch of horizontal movement since last season.

He spent his offseason with a Rapsodo machine working on his curveball as well, which has become a true 12-to-6 pitch with more vertical drop and less side-to-side movement. His changeup also gained more vertical drop. If you plot this all out in the strike zone, everything is moving away from Weaver’s fastball — each pitch is a more distinct offering.

Imagine in the GIF below if Weaver’s changeup and curveball dropped less and his cutter did run as much. They would be closer to the center of the zone. While factors like location matter, the focus here is on the amount of movement after an individual pitch reaches the tunnel pointat which a hitter needs to commit to a swing.

Video credit: MLB

Video credit: MLB

This may seem like too granular of a detail for a pitcher to manipulate, but I asked Weaver how deliberate the action was to separate his pitches to different parts of the zone. “Yes, there were thoughts behind it that were pretty in-depth,” Weaver said. “But I think more than anything I’m just a feel guy.”

A “feel guy” with a Rapsodo machine and a revamped repertoire.

These peripheral improvements are featured more versus right-handed hitters, coming only in small doses to left-handed hitters. As Weaver says time and time again, his changeup has always been his best pitch, made particularly clear by his usage of the two pitches against left-handed hitters over 85 percent of the time. “I got down to maybe being a two-pitch pitcher at times [last season],” Weaver said, signaling a need for correction.

Weaver mentions iterations of this quote often, yet his two-pitch dependency against left-handed hitters has actually increased from 2018 to 2019. If you’re a left-handed hitter facing Weaver, nearly nine out of 10 times you’re going to see a fastball or changeup. It works, in part, because his changeup has returned to form. A starting pitcher can sometimes survive with two pitches if both pitches are very good — most notably Chris Paddack or Luis Castillo, when talking about current fastball-changeup combinations.

However, Weaver’s changeup is not as good as that of Paddack or Castillo. Weaver’s infrequent usage of his third and fourth pitches to left-handers are effective given that both have become average pitches for the first time in his career. Even if the third/fourth offerings combine for only 16 percent usage against left-handed hitters, the quality of each pitch matters.

“More than anything, the adjustment for me wasn’t necessarily trying to rebuild or do anything,” Weaver said. “It was just trying to take the pitches I had and just throw them better … when I can mix in a repertoire where they can’t sit on things it opens things up for me.”

With four pitches, Weaver has evolved into a new pitcher. PECOTA projects the Arizona right-hander for a 3.69 ERA over the remainder of the season and the Diamondbacks are hoping he can emerge as a dependable no. 3 starter behind Zack Greinke and Robbie Ray.