Maybe We Should All Learn the Split-Finger

Swinging strikes are the best. The batter tried to make contact and failed in a head-to-head matchup of will and strength and coordination. That moment is also great, statistically. Swinging strike rate is a per-pitch metric — meaning they become meaningful much faster than per-plate-apperance metrics — and it represents the closest proxy we have to ‘stuff’ that’s easily available.

That said, the fastball is still king, and it has the lowest swinging strike rate of any pitch. The league throws the pitch almost 60% of the time, after all. And if you’re throwing them as much as Shelby Miller and Jordan Zimmerman throw their fastballs, your swinging strike rate is going to suffer. That’s how two great young pitchers have such modest swinging strike numbers.

Is it possible to judge how many more strikes a pitcher with a certain arsenal is getting over a mythical pitcher (Average McAverageson) with the same arsenal where every pitch is league average? Yes. Yes it is.

Thanks to one of my favorite posts to link to, a great library piece by Harry Pavlidis that provides swinging strike benchmarks for each type of pitch, we can actually take a pitcher’s arsenal and create a sort of “expected” swinging strike rate based on how often they throw each pitch. Fairly straight-forward actually.

Of course, the pitchers that find themselves at the top of this list of qualified starters from 2013 are just pitchers who have multiple great pitches. I mean, Pitcher McPitcherson stands atop the qualified leaderboard. (Starters showed a league-wide 8.7% swinging strike rate in 2013.)

There might be a couple overachievers on this list — Kris Medlen and Patrick Corbin both do more than a pitcher would with an average version of their arsenals, but they look a little out of place on this list — but by and large, the pitchers on this list are all excellent. They have excellent pitches! Amazing!

Perhaps the bottom of the list will be more enlightening.

There are some surprises on this list, but for the most part it’s the Unimpressive Stuff list. The top guys on this list have representative offspeed offerings, but until you get about five or six deep, there isn’t a pitch that you could hang your hat on. Many of these pitchers throw a two-seamer primarily, as you can see the four-seam fastball percentages are pretty low, with Kyle Kendrick pulling up the rear. And in general, this group seems to survive on command — they’ve got a 6.7% walk rate as a crew. If you don’t have stuff, you better be able to put it where you want.

At first it was very surprising to see Matt Cain show up here. But then I looked at his per-pitch peripherals last year, and there it was. Only the change-up, of his five pitches, had an above-average swinging strike rate. All of them are close to average… Well, it could have been a one-year blip. His fastball actually used to get a lot of whiffs. Back in the halcyon days of 2012.

And put this in your back pocket: The under-performer with the highest actual swinging strike rate just added a split-finger this year.

Maybe most interesting are the pitchers that, in 2013, featured exactly the swinging strike rate a pitcher with an average version of their arsenals would feature.

Weird, huh? Jeremy Hellickson gets there by having two below-average pitches, one average pitch, and one outstanding pitch. But it’s no brain-buster to say he’s an average pitcher — his FIP was right on the league average last year. As good a pitcher as Rick Porcello is, he’s actually average across the board — where his sinker gets a few more whiffs than usual, his new curve (which helps him bust platoons) is worse than average and drags him back to average. He’s about ground balls at his core, anyway, so swinging strikes may not be his goal.

But Hisashi Iwakuma. He’s not about grounders in the same way at least. He had a gaudy swinging strike rate even (10.3%, good for eighth among qualified starters in the American League last year). It’s a little strange to say that he did just about as well as a major league pitcher throwing his mix of average pitches would do. But on a per-pitch level, he has two above-average pitches by whiffs — the four-seam and the split-finger — and his slider, sinker and curve are all below-average by whiffs.

With split-fingers enjoying the best whiff rates in baseball — a 16.6% swinging strike rate built on the highest swing *and* whiff-per-swing rates — this does illustrate how a pitcher with a good four-seam and split-finger can make his entire arsenal play up, even if the rest of the pitches are sub-par. After all, Iwakuma’s swinging strike rate would have been expected of someone who threw a mix of entirely average pitches that included an average split-finger. And yet his swinging strike rate was in the top ten. Maybe we should all learn split-fingers. Maybe Masahiro Tanaka is about to outperform his projections.