You might think the rarest pitch in the game is the knuckleball — only two pitchers regularly throw it right now. But there is a pitch that only Brad Ziegler throws often.

Ziegler throws a changeup — out of a submarine arm slot. Nobody else throws the same pitch with the same mechanics.

Only six sidearmers threw at least 25 changeups last year, and if you up that number to 100 thrown, there’s only Ziegler and (lefty) Aaron Loup on the list. If you limit the list to just submariners, Ziegler’s the only one that throws a changeup regularly.

Turns out, the physics of throwing a ball from that angle could be the reason so few sidearmers boast a solid changepiece.

Take Ziegler’s slider as an example. Back when he threw overhand, before 2007, he was putting traditional slider spin on the ball from his old arm slot. Thanks to Matt Lentzner at The Hardball Times, we know what that slider spin looks like. From his piece, here are the spins on the ball on pitches leaving from your traditional three-quarter arm slots:

Read the rest on Just a Bit Outside.