Stephen Strasburg doesn’t throw the ball as hard as he used to. In 2010 his fastball averaged (97.6) above his max from this year (96.9). Whether that’s by choice, the cruelty of age, or years of wear and tear is beyond the scope of this article. In fact, I’m here to extol the virtues of a Strasburg pitch that goes much slower but is no less cruel and punishing. I’ll take a moment to discuss Strasburg’s changeup.
In reality, Strasburg is blessed to throw three great pitches: a blazing fastball that sets up one of the best curveballs in all of baseball and a changeup so inhumane that the UN should classify it as abuse. How filthy is his change, and how do we track it? Luckily, we have PITCHf/x data to answer those very questions.
Over the years, Strasburg has primarily thrown his fastball (whether that be classified in PITCHf/x as a general fastball or as a 2-seamer) from anywhere between 73.5% of the time in ’12 to a low of 57% of the time this season. He’s used his change roughly 16% of the time, fluctuating somewhat but holding steady in this general range, until we get to this season when Strasburg has relied on the pitch more than ever. How much? He’s using his change 25.74%, or 1 in every 4 pitches. The increased reliance on the pitch hasn’t diminished its effectiveness, though. Looking at the chart below, we can see the end results over the years.
We can dismiss 2011’s data since Strasburg pitched in only a handful of games, and he threw the change a grand total of 43 times. Not exactly telling us much. But, ISO (Isolated Power) and wRC+ (Weighted Runs Created compared to league average) can give us a better idea how batters have responded to the pitch. In short, not well at all. ISO gives a pretty clear indication that batters are unable to square up the pitch and drive it for extra bases. 100 is average in regards to wRC+, and from the table above it’s clear to see that when Strasburg throws his change, over the last two years it’s created 85-87% fewer runs than average. In other words, Strasburg’s change has been impressive.
Additionally, when we look at the change strictly through events, we can see that the pitch in relation to his others has been dominant:
Under type, FF and FT refer to four-seam and two-seam fastballs respectively, CH is changeup, CU is curveball, and SL is slider. The key figures I’d like to point out are the ridiculous 25.7% of swings and misses and the 12.9% of changeups put into play, lowest of all his pitches. When batters do put that ball in play, 69.6% of those are ground balls, easily the highest this season of all his pitches.
It’s also interesting to see how Strasburg uses the pitch against both righties and lefties:
Against right handed batters, Strasburg tends to throw the pitch inside, a particularly dangerous proposition to a left hander who traditionally have hit low and inside well. Strasburg’s change mostly remains in the lower third of the zone, which is sound strategy if you’re going to miss with a pitch thrown at 87 MPH.
Strasburg attacks lefties with his change low and outside primarily. In fact, nearly half of the changeups thrown to lefties have been tailing away, inducing them to chase.
None of this exists in isolation of course. His fastball obviously sets up the use of changeup and curve, and the argument here isn’t that Strasburg should rely on his changeup and turn into a right-handed version of Tom Glavine. Instead, we should appreciate Strasburg’s ability to effectively change speeds and keep the batters off balance.