April 13, 2017

Flu-Like Symptoms

The Scary Consequence of the Strikeout Scourge

by Rob Mains

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In Monday’s Giants home opener, Diamondbacks right-hander Taijuan Walker hit Buster Posey in the head with a pitch in the first inning, forcing him from the game. Posey has been placed on the seven-day concussion disabled list.

I’m not going to link to the pitch here. You can find it easily enough if you want to watch it. I don’t, because I find these plays terrifying. They speak to a concern of mine: That baseball is heading toward another Ray Chapman moment, or something close, and I don’t know what can be done to prevent it.

Admittedly, this is a hobbyhorse of mine. I made a presentation about it at the SABR Analytics Conference in 2016, and I’ve alluded to it in the past. But I’ve never gone into it in depth here at Baseball Prospectus, so I’m going to today. If you’ve already heard my full rant, there’s a lot of other good content here today that you can check out. Have a good weekend and I’ll see you Monday.

I worry about a batter getting killed, or at least seriously hurt, by a pitched ball for three reasons.

1. Pitchers are throwing harder and harder. You already know that.
2. Hit batters are near all-time highs. You may or may not know that.
3. That’s likely to continue, because hit batters are linked to rising strikeout rates. That’s not intuitive, so I’m going to try to persuade you.

Regarding pitch speed, I assume I don’t need to convince you. And, of course, the up-in-the-zone pitch (i.e., closest to batters’ heads) of choice is the four-seam fastball, which is also the fastest pitch in pitchers’ arsenals. The pitch that hit Posey was a 94.2 mph four-seamer.

To the second point: Here’s a chart showing plate appearances per hit batter. The fewer plate appearances, the more frequent hit batters are, so I’ve reversed the scale here.

Batters were hit last year at the 12th-highest rate since the American League was formed in 1901. There have been only 31 seasons during which batters were hit more frequently than once every 125 plate appearances: Every year from 1901 to 1911, and every year starting in 1997.

Somebody’s going to look at that and say, “Well, duh, pitchers are being rushed to the majors before they learn the strike zone,” to which I’d reply, “You’ve been watching too much Tyler Glasnow.”

Walks, in fact, are near a postwar low. Pitchers today have outstanding control. That’s not why they’re hitting batters. The reason, I’d posit, is strikeouts. No, really.

Let me give you an example. You know who leads the majors in hit batters over the past three years? Chris Sale, with 41. Sale, of course, is a fantastic pitcher, who both strikes out a lot of batters and limits walks. His 5.7 K/BB ratio was second to Clayton Kershaw among pitchers with at least 500 innings in 2014-2016.

Since Sale’s left-handed, he faces a large proportion of right-handed batters. From 2014 to 2016, 83 percent of the batters he faced were right-handed. (The major-league average was 57 percent.) Here’s his heat map vs. right-handed batters over those three years.

Those five squares along the left side are the ones closest to right-handed batters, the ones where there’s a possibility of a batter getting hit. Those five comprise 15.3 percent of Sale’s pitches.

But if you break down Sale’s pitches to when he’s ahead in the count compared to when he isn’t, a different picture emerges. Here’s Sale against right-handed batters from 2014 to 2016 when he’s ahead 0-1:

And 0-2:

And 1-2:

The percentage of Sale’s pitches along the left-handed side of those heat maps, where there’s HBP risk, are 17.8, 21.2, and 18.8, respectively. All told, when Sale’s ahead in the count, he’s out of the strike zone and inside on 19.0 percent of his pitches. When he’s not ahead, that proportion drops to 13.5 percent.

So what’s going on? Why is Chris Sale over 40 percent more likely to throw a pitch that’s inside when he’s ahead in the count?

Well, it’s not hard to figure out. When pitchers are behind in the count, they try to locate in the zone in order to avoid a walk. When they’re ahead, they work outside the zone in order to induce the batter to chase, generating a whiff or weak contact. I’m oversimplifying a lot, but the basic idea is that pitchers play along the margins of the zone when they’re ahead in the count more than when they’re behind. And when you’re at the inside fringe of the zone, and you miss, you might hit a batter.

This is borne out in the numbers. Here’s a simple table showing the hit by pitch rate when pitchers are ahead in the count (0-1, 0-2, 1-2), behind (1-0, 2-0, 3-0, 2-1, 3-1, 3-2), and even (0-0, 1-1, 2-2). This data is from Baseball-Reference, and the count is the count when a plate appearance ends, i.e., the count when the batter gets hit. Again, this data is from 2014 to 2016.

As you can see, a batter is 2.7 times more likely to be hit when the pitcher’s ahead in the count than when he’s behind.

To this point, I think this is all pretty intuitive. But let me tie that into strikeouts. Strikeouts are up, of course. They’ve risen in each of the past 11 seasons, and there’s been a new all-time record set nine straight years. In most cases—55 percent of strikeouts last year—they’ve occurred when the pitcher’s ahead in the count (0-2 and 1-2). And as strikeouts have risen, pitchers have been ahead in the count a lot more. Here’s the breakdown since 1990:

In 2014 and 2015, for the first time in history, plate appearances ended with the pitcher ahead in the count more often than hitter. That trend receded a bit in 2016, but the difference was still the third-smallest in history. (Granted, we don’t have pitch count data going back very far, but I feel pretty confident saying that we’re seeing historical extremes, given the relatively recent spike in strikeouts.)

As recently as 2000, plate appearances were 10 percent more likely to end with the batter ahead. In 2016, the difference in the count was less than one percent. That’s what the problem is. The hit batter rates were similar by count: 263 plate appearances per hit batter when the batter was ahead in 2000 vs. 222 in 2016; 80 plate appearances per hit batter when the pitcher was ahead in 2000 vs. 87 in 2016. (With the count even, batters were hit once every 90 plate appearances in 2000 and 100 in 2016.)

So the problem isn’t that pitchers are trying to hit batters, or even that the rate is much different, once you take count into effect. It’s that with strikeouts rising, an increasing proportion of plate appearances are occurring on counts when batters are likely to be hit. The strikeout scourge is putting more and more batters in harm's way, and with pitchers throwing harder and higher, the harm is becoming potentially cataclysmic. This is a real problem, and I don’t know what the solution is.

Thanks to Rob Neyer for coining the term “strikeout scourge.” I really like it. Thanks to Rob McQuown for providing data for this analysis literally faster than I could ask for it.

Rob Mains is an author of Baseball Prospectus. Follow @Cran_Boy
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