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Monday, April 26, 2021

Are Pitchers Being More Aggressive With the New Ball?

This is not solely an investigation into deGrom; he is just emblematic of what might be a league-wide trend. Through games played on April 24, 55% of four-seam fastballs were in the strike zone — a figure that, if it holds, would mark the highest four-seam Zone% of the pitch tracking era. Though more four-seam fastballs have been thrown in the strike zone in recent years, 2021 represents a statistically significant tick up, with a p-value of practically zero.

League-wide four-seam fastball Zone% had been extraordinarily stable over the last eight years: From 2013 through ’20, it never rose above 53.7% and never fell below 53.1%. Even looking at this rate on a month-to-month basis, it did not vary significantly: Since 2018, the highest monthly four-seam Zone% was 54.6, in August of that year, which is the only month that falls within the 95% confidence interval for the “true” 2021 four-seam Zone% thus far.

There could be all sorts of reasons why we’re seeing this league-wide shift — and we can’t totally rule out noise — but my first thought was that pitchers are feeling more comfortable attacking the strike zone with the new baseball. Indeed, we’re seeing this uptick mostly occur among fastballs thrown at least 95 mph. If you’re worried less about giving up the long ball, why not pour more hard fastballs in the zone? After all, pitchers are throwing harder again this year, so if fewer non-squared-up baseballs are going for extra-base hits, then they may feel as if they have much more margin for error and can throw more pitches in the zone.


RoyalsRetro (AG#1F) Posted: April 26, 2021 at 05:55 PM | 0 comment(s) Login to Bookmark
  Tags: juiced ball

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