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Finding Stephen Strasburg's missing strikeouts

Stephen Strasburg's strikeout rate is down. What gives?

Ah-ha! He's too far from the mound!
Ah-ha! He's too far from the mound!

It's the beginning of the season. But it's not quite the beginning beginning. Not everything has to mean something, but some things are starting to have meaning. We're over a quarter of the way through the season, which is juuust about where we can start freaking out over unexpected performances.

Which brings us to Stephen Strasburg. The combination of him a) returning from injury last spring and b) getting shut down last year makes me think of Strasburg as a pitcher returning from injury this season. He's not. He's a healthy pitcher who is especially rested, if anything. But if you're looking for early-season red flags, here you go:

Strikeouts per nine innings:
2012: 11.1
2013: 8.6

Strikeouts per plate appearance
2012: 30.2%
2013: 23.3%

Or, in graph form:


That trend is STRAIGHT DOWN!

After Strasburg sat for the end of the 2012 regular season and the playoffs, he's striking out fewer batters than ever before. This is something that requires some intrepid investigation. A rundown of likely suspects:


Min. fastball velocity, 2012: 91.8 m.p.h.
Min. fastball velocity, 2013: 92.0

Avg. fastball velocity, 2012: 95.8 m.p.h.
Avg. fastball velocity, 2013: 95.5

Ah-ha! Wait …


Horizontal movement on fastball, 2012: -5.02 inches
Horizontal movement on fastball, 2013: -5.54

Vertical movement on fastball, 2012: 9.29 inches
Vertical movement on fastball, 2013: 9.11

Horizontal movement on curveball, 2012: 7.44 inches
Horizontal movement on curveball, 2013: 8.63

Vertical movement on curveball, 2012: -6.25 inches
Vertical movement on curveball, 2013: -7.88

Horizontal movement on change, 2012: -8.64 inches
Horizontal movement on change, 2013: -8.30

Vertical movement on change, 2012: 2.53 inches
Vertical movement on change, 2013: 2.77

Ah-ha! Wait … I dunno, maybe his curve is slurvier? It's not as 12-to-6? By an inch.

No. No, that's probably not it.

Swing percentages

Swing rate on fastball, 2012: 44.9%
Swing rate on fastball, 2013: 48.9

Swing percentage out of the strike zone on fastball, 2012: 63.7%
Swing percentage out of the strike zone on fastball, 2013: 68.9

Swing rate on curveball, 2012: 34.7%
Swing rate on curveball, 2013: 28.7

Swing percentage out of the strike zone on curveball, 2012: 38.4%
Swing percentage out of the strike zone on curveball, 2013: 29.7

Swing rate on change, 2012: 52.7%
Swing rate on change, 2013: 46.8

Swing percentage out of the strike zone on change, 2012: 78.4%
Swing percentage out of the strike zone on change, 2013: 60.0

Ah-ha! Hitters aren't chasing after his curve and change like they did last season! I knew it! It's probably something to do with his release point. No, his mechanics. His inverted W! His spread-legged M! His disinterested Q! There's someth …

Pitches thrown

Curveballs, 2012: 493
Curveballs, 2013: 171

Changeups, 2012: 414
Changeups, 2013: 154

Hitters have swung at 10 fewer curveballs than you would expect based on last year's rate. They've swung at nine fewer changeups. That could mean something. That probably doesn't mean anything. If you're skeptical of a hitter hitting .200 or .400 over 171 at-bats, you should also be skeptical of the swings a pitcher gets over 171 pitches thrown.

A reminder, this is what a supposedly hittable Strasburg looks like:

He's still almost certainly one of the best pitchers in baseball. Even though his strikeout rate is more Tommy Milone than Pedro Martinez right now, that isn't going to last. We're a quarter into the season. Expect Strasburg to strikeout more hitters over the next three-quarters.