Shortly after the Mariners made the mistake of trading Brandon Morrow for Brandon League and another guy, it was noted by the Mariners’ front office that, the season before, League had thrown baseball’s most unhittable pitch. No pitch in baseball, apparently, generated a lower contact rate against than Brandon League’s splitter, and that gave us Mariners fans something to look forward to. What it actually wound up doing was give us something to complain about all the time, but no matter. That was the first I’d personally heard of a most unhittable pitch, and I fell in love with the concept. What better measure of dominance than whiffs over swings?

Of course, we all understand that pitches don’t exist in isolation. That year, League’s splitter was baseball’s most unhittable pitch, but it wouldn’t have been so if League only ever threw his splitter and never threw his fastball. There’s a lot of game theory stuff at play, so isolating individual pitch types is a little improper and misleading. Still, it’s a fun exercise, and I’m about to indulge. So we’re all about to indulge.

Just recently Baseball Prospectus folded in PITCHf/x leaderboards, based on Brooks Baseball data. I found myself navigating the leaderboards this afternoon, and I grew curious about 2012’s most unhittable individual pitch. I decided that I only wanted to look at starters, because relievers throw fewer pitches and have very different jobs. I also decided that I wanted a minimum of 200 pitches thrown, to weed out some small-sample noise. Not that there isn’t still noise, and not that I’ve made any correction for game-theory data or count, but whatever, I knew what I was getting into. This left me with a pool of 632 pitchers and pitch types. The pitcher and type with the lowest contact rate: Stephen Strasburg, changeup, 46-percent contact.

PITCHf/x recorded Strasburg throwing more than 400 changeups this season. Batters swung at 219 of them, and of those swings, 119 completely whiffed. Less than half the time batters swung at Strasburg’s changeup did their bats so much as touch the baseball in flight. It’s not far and away the most unhittable pitch in the sample, but the gap between first and second does appear wide enough to hold through the end of the year. It’s not like Strasburg is going to be throwing anymore changeups.

For good measure, Strasburg’s change also generated a grounder two out of every three times it was put in play. But, as noted before, it was very seldom put in play, so I don’t know how much this matters. It was a good pitch, is the point.

The predictable thing to do here would be to show .gifs of Strasburg generating swinging strikes with his changeup. He did that very often, and the .gifs would allow you to visualize what the pitch looks like, if you can’t recall it off the top of your head. Instead I’m going to show you .gifs of the two times Strasburg’s changeup was hit for a home run. You can still visualize what the pitch looks like, but now it’s all been turned on its head! Wacky!

The first batter to take Strasburg’s changeup deep was Jose Bautista, and there’s hardly any shame in that.

The second batter to take Strasburg’s changeup deep was Tyler Colvin, and there’s some very limited shame in that. Although it’s not like Colvin identified the pitch out of the hand and hit the living crap out of it.

I still can’t figure out how that swing made that ball leave that yard, but it did, and I suppose one of the lessons here is that even a very good pitch can be drilled for a home run and nothing is automatic. Baseball’s most unhittable pitch — by a stater — was not actually unhittable.

Strasburg has a good changeup — this we know. This we basically just confirmed. It stands to reason that a big part of the pitch’s effectiveness is that the hitters have to look out for the heat and the slurve. Strasburg is known for his high-90s fastball, and he’s always had this devastating breaking ball, and including a changeup is some degree of unfair. What’s interesting is that people weren’t really talking about Strasburg’s change as a weapon at the time he was drafted. Strasburg said in college he just sometimes mixed the pitch in. This draft report essentially labels the change as inconsistent. Quote:

Nitpickers may look at the secondary offerings as being just average and his command needing a little refinement, but none of that will keep him from being atop just about every Draft board.

Strasburg’s long thrown a changeup, but it never got the attention that his fastball did, or that his breaking ball did. He does indeed have a very good fastball and a very good breaking ball, but his changeup looks to have been baseball’s most unhittable regular pitch by a starter in 2012. Ending be damned, this was a pretty good season for Stephen Strasburg.