what's the purpose of an off-speed pitch?

AL BEast Notebook - April 17

In the bottom of the fourth inning on Tuesday, the Yankees were trailing the Diamondbacks 2-0. With one out and runners on first and second, Brandon McCarthy was pitching to Robinson Cano.

McCarthy threw a slider outside, another slider in the dirt, then a changeup for ball three. Cano taking all the way, the next pitch was a changeup right down the middle, followed by a slow inside curveball that was fouled away.

The sixth pitch of the at bat was yet another changeup, right down the middle, and Cano blasted it to Timbuktu.



So yeah, what is the point of an off-speed pitch, specifically a changeup? To interrupt the batter's timing and keep him off balance. So why in the world is the pitcher throwing six off-speed pitches in a row? I think Robinson Cano is perfectly capable of hitting an 84 mph fastball, and when you don't throw a real fastball to him--throwing six consecutive slower pitches--that's all a changeup is!

Cano's hit was a three run shot that was just crushed. Yankees won the game 4-2.

Dear Brandon McCarthy: you have a 94 mph fastball; use it. Otherwise you might as well be Jamie Moyer, and Jamie Moyer isn't sneaking an 84 mph fastball past Robinson Cano.