The Case for Slowing It Down

Since 2015 (i.e., the Statcast era), just 0.3% of all pitches thrown in MLB have been under 70 mph; pitchers today generally live in velocity bands from 10 to 30 mph higher. Being able to slow the ball down to such an extreme degree without tipping off the batter to what is coming is not trivial, and being able to drop these pitches in for strikes takes practice. Taking time in a throwing session to lob lollipops into the strike zone probably seems foolish to many pitchers, especially if they can just throw 95 mph instead.

I understand the roadblocks to throwing slow looping curveballs. But whenever I see a pitcher throw them, they often seem to disarm the batter, who usually doesn’t swing. In that scenario, the worst-case result is often a ball, and if the pitcher can locate the pitch, he can nab a strike with little resistance. And as fastball velocity continues to increase across the league both this year and in seasons past, pitchers are increasingly leaning on breaking balls and offspeed pitches to fool hitters who are geared up for heat. With that in mind, a super-slow curveball could be a useful weapon.

Is my intuition correct? To test it, I decided to pull up every pitch since pitch tracking began in 2008, via Baseball Savant, and filtered for those that traveled less than 70 mph and were labeled as a curveball or eephus. The tricky part here was that a lot of those pitches were thrown by position players, which complicates my thesis because (surprise) position players are bad at pitching. To counter that, I downloaded all the team rosters since 2008 from Retrosheet, then selected all the pitchers in the dataset and filtered the pitch data with the condition that the player throwing the pitch appeared in the list from Retrosheet.