Great article here by Joe Sheehan that breaks down every pitch Mariano Rivera threw last season. Take a look at the chart: lefthanded hitters were fed exclusively the cutter and could do nothing with it: 23% of the time they swung, they missed, and the 30 times they did put the ball in play, it only yielded 10 total bases. Wow.
Here’s Sheehan’s take:
The thing to notice here is that Rivera throws only cut-fastballs when facing LHH. Of the 188 pitches he threw to LHH, 187 were cutters. Wow. Up in the count, down in the count, with runners on, or with the bases empty, LHH know with almost total certainty that Rivera is coming with a cutter. There is no other pitch in the back of their mind that they might see…yet they still can’t hit it. They miss 23% of the time they swing and even when the ball is put in play, it isn’t hit with any type of authority. I’m completely mystified at how Rivera is able to be a one pitch pitcher to lefties. I’m open to suggestions, but I think Rivera’s cutter to a left-handed hitter is the best pitch in baseball.
And of course I have to agree, though in my mind it’s not just the best pitch in baseball, but the best ever. Batters know it’s coming, they can’t hit it, and it can be thrown for a strike. I mean, come on, there may be some pitches that hitters cannot hit, but generally they still rely on deception: usually they’re balls that hitters think is a strike. Like Joba’s slider that falls off the table: it is set up by the explosive fastball. If hitters knew the slider was coming, they just wouldn’t swing because it’s rarely a strike. If you don’t swing against Rivera, you go down looking.