Tom Verducci celebrates the 150th anniversary of the curve ball. I very much like the explanation of why Clayton Kershaw throws such a devastating curve:

Oddly, there is almost nothing spectacular about the metrics of Kershaw’s curve. It spins (2,373 rpm) more slowly than the average curve (2,500), and also travels (73.3 mph) more slowly than average (77.8). The wizardry of Kershaw’s curve is in how much it resembles a fastball out of his hand. Kershaw throws each pitch from an identical release point, depriving hitters of an early “tell.”

Kershaw also disables hitters’ second level of decoding: the reading of spin. Four-seam fastballs have true backspin; they rotate so fast over the poles of the baseball that no spin is discernible. The ball appears as a gray circle. Curveballs rotate in the opposite direction—they have topspin—but slow spin or a tilted-spin axis can reveal to the hitter streaks of red across the gray circle, a tip-off from the spinning seams that the pitch is a breaking ball.

Kershaw spins his curveball at a similar rate to his fastball (2,326 rpm). Though they spin in opposite directions, because he throws both with a true overhand delivery, creating pole-to-pole rotation, the pitches first look exactly alike to a hitter: a gray circle. The four-seamer holds its plane while the Kershaw curve can drop nine inches.

The article is interesting throughout, but the way the page renders on my chrome browser makes it difficult to read. The photos take a long time to load, and ad that keep popping in and out change the placement of text on the page. You may want to wait a minute for the page to completely load before you start reading.