The Brewers' Jackson Chourio finished his breakthrough 2022 season at Double-A as an 18-year-old. No hitter that young had reached that high since Fernando Tatis Jr. in 2017 or Bryce Harper in 2011.
Chourio returned to Biloxi on Opening Day this year as the only 19-year-old at Double-A. The center fielder did not light the world on fire in the first half, hitting .249/.304/.410 with 11 home runs and a 21% strikeout rate in 71 games.
But not everything is as it seems.
The Southern League experimented with a pre-tacked baseball in the first half that gave pitchers a consistent grip on the ball. It had the effect of improving spin rate and command of breaking pitches and fastballs, especially riding four-seamers up in the zone.
The SL ditched the pre-tacked baseball when the second half began on July 14. In his first 30 games coming out of the break, Chourio batted .346/.401/.554 with six homers and 15% strikeouts.
Chourio's batted-ball data was equally bullish. According to Synergy, he improved his swinging-strike and chase rates when the SL moved to a standard baseball in the second half. He also swung much less frequently overall.
Chourio saw his greatest gains against fastballs. His chase rate against them dropped from 33% to 21%. His swinging-strike rate improved slightly 18% to 17%. Most dramatic was his change in swing rate versus fastballs, which fell from 53% to 39%.
Most of Chourio's improvement against fastballs occurred with heaters high in the zone-the pitch type on which pitchers received the biggest performance boost with the pre-tacked ball.
This story is from the September 2023 edition of Baseball America.
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This story is from the September 2023 edition of Baseball America.
Start your 7-day Magzter GOLD free trial to access thousands of curated premium stories, and 9,000+ magazines and newspapers.
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