The yellow hammer. Uncle Charlie. Lord Charles. Public Enemy #1. The Hook. Yakker. Deuce. The Spinner. Does any pitch in baseball have as many nicknames as the curveball? Is there a pitch more compelling than a sizzling, spinning breaking ball that falls off the earth?



I submit that there isn’t. And yet, it’s not always the easiest pitch to use. Batters swing at curveballs less often than any other pitch type, and so the average whiff rate (11 percent) is lower than it is for any other non-fastball. The pitch gets more grounders than any other non-fastball, also, but lord help the pitcher that hangs one trying to steal a strike.



At the same time, it’s not so difficult to see what makes a good curveball, at least compared to the fastball.



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Curveball velocity stands out as having a tight relationship with outcomes, and drop is also good. That’s the...