The Adjustment That Stopped Andrew Vaughn’s Whiffs

In late June, Chicago White Sox rookie and 2019 third overall pick Andrew Vaughn had a 13-game stretch where he struck out 31% of the time with a 15.1% swinging strike rate. This slump brought his season-long wRC+ down to 91 and his K-rate up to 27.2%. It was a disappointing start to the career of a prospect who was seen as having a great hit tool and had always had below-average strikeout rates in the minors. That stretch culminated in a three-game series against the Mariners that saw Vaughn strike out four times in eight plate appearances and wave through 20% of the pitches he saw:

The White Sox had a day off the next day and by the time their next series against the Twins started on June 29, Vaughn had snapped out of his funk. In fact, he didn’t whiff a single time in the series against Minnesota. When watching his swing in that series, you could notice an adjustment beginning to take shape. Focus on his hands, compared to the swings you saw above:

Vaughn’s ability to make contact has continued and since June 29, his swinging strike rate is an elite of 6.3% — that’s Juan Soto territory. Now that we are into August, Vaughn’s new hand load has solidified further, making it easier to see the difference compared to his early season swings. Here’s a better look at the adjustment:

His pre-swing is less erratic in general but more importantly, I want to focus on the load-phase and how his hands are getting ready to drive to the ball. Here’s a zoomed in shot that only shows the time from when his hands start loading to when he makes contact:

You’ll notice his hands used to start higher up and then loop downward more, making a circle back to their loaded position. He’s all but eliminated that downward movement; his hands start in a lower spot making it a near straight-line back. This abbreviated movement gets his hands in position to drive forward sooner. The difference may be small but it could be giving him a more repeatable drive to the ball as there is less movement that could deviate the start of his swing path.

It doesn’t appear as if this more direct hand movement is entirely new to him either; if you take a look at some of the pre-draft scouting video of him, you’ll notice he didn’t have the loop in his hand-load that he had early this season. Vaughn has returned to having quieter movement with his hands and the result has been much more consistent contact:

If you look at Vaughn’s season before and after the adjustment with his hands, you can see that the change in his performance goes well beyond whiffing less often. His results have gone through the roof:

Vaughn has cut his strikeouts in half while hitting for more power. You can see the importance of his lower K-rate when looking at his StatCast results over that time:

Typically during a hot stretch like this you might expect a player’s exit velocity to jump as well, but Vaughn’s has actually gone down. It’s possible this adjustment has cost his swing a slight bit of thump, which isn’t all that surprising given how much contact he has unlocked. And putting the ball in play nearly twice as often is more than making up for the slight dip in exit velocity. For example, his barrel%, which is based on balls in play, has dropped a small amount while his rate of barrels per plate appearance has actually gone up, suggesting that his contact-oriented swing isn’t actually costing him barrels. This is also partly due to him hitting more fly balls, which means he’s making better use of his hard contact:

This surge from Vaughn is made all the more impressive given some of the developmental roadblocks he’s had to push through this season. For one thing, he has very little professional hitting experience. Prior to making the White Sox Opening Day roster, Vaughn had never played above High-A. He skipped the two most advanced levels of the minor leagues in part because the pandemic cost him a 2020 minor league season and also because a late spring training injury to Eloy Jiménez created a need to expedite his development. Vaughn has seen a huge jump in pitcher quality this season and if that wasn’t enough, he has also been asked to play a new position. Vaughn has only made four starts all year at his natural position of first base as he was asked to plug the left field hole that Jiménez had left open. He’s also done some emergency work at third and second base and is now transitioning over to right field with Jiménez back in the lineup.

Given all that, Vaughn’s season, even with a 118 wRC+, has to be viewed as a huge success and a harbinger of his future role in the middle of Chicago’s lineup. That’s not to say there aren’t still things to be worked on. Vaughn’s swing decisions haven’t really shown much sign of improvement over this recent stretch. His propensity to swing out of the strike zone has been about the same all season long, with a slightly worse than league average O-Swing% of 32.6%. That isn’t a big issue but for someone who is expected to eventually draw a lot of walks, it is notable that his walk rate has dropped a touch and remains below average (league-average is 8.8%) even after this swing adjustment. It seems possible that his quicker, more abbreviated load might allow him extra time before making his swing decision. It’s notable then that after a 15-game drought of not drawing a single walk, he’s now drawn seven in his last seven games — with a 26.1% O-Swing during that stretch. The walks seem to be coming.

Another issue that Vaughn is working through is his difficulty against breaking balls. Again, it’s not all that surprising considering his lack of high-minors experience but check out how he’s fared by pitch category, as well as how often he sees them.

Vaughn torches fastballs. His .396 wOBA against them goes up to .415 on pitches 95 mph or faster. His rate of fastballs seen has actually increased to 58% since July 1. It may seem surprising that a rookie who has excelled against fastballs is still getting so many of them. Either pitchers haven’t noticed or they just think their fastball is good enough. Frankly, he’s probably lucky to still be seeing a league-average number of fastballs as his numbers against breaking balls suggest pitchers should be attacking him with benders instead.

Vaughn has struggled against sliders (.240 wOBA) but it’s curveballs that have been the bigger issue, as he has just a .136 wOBA — well below the .261 league average. Similar to how the fastball usage against him is going in a confounding direction, the number of breaking balls he’s seeing is actually dropping. He’s seen only 33.3% breaking balls since July 1, and even fewer so far in August.

The cat and mouse game between young players and the league is always fascinating. We’ve already seen an impressive adjustment out of Andrew Vaughn this season, as he’s drastically cut down on his whiffs seemingly thanks to a quieter and more direct hand-load. Now his struggles with breaking balls have become apparent; it seems time for the league to force him to fix that issue as well. Given his talent and the fact that we’ve already seen him push through a period of struggle, I have little doubt that Vaughn will begin showing improvement against breaking balls, especially once he inevitably starts seeing more of them.