Soaring Strikeouts: It’s not just the 2-strike approach

The MLB strikeout rate has risen 35% since 1988, climbing from 14.7% of all PAs to 19.8% in 2012. It’s not all the batters’ doing, and I’m not here to berate them, anyway. I just want to look at two basic parts on their side of the K-rate equation. Let’s show the basic rate before we break it down:

SO per PA 1988-2012

 

When we talk about the hitters’ role in K rates, we most often speak of their 2-strike approach. Modern hitters are less likely to cut down their swing with 2 strikes, or to swing at a pitch they can’t drive. So once they have 2 strikes, they’re more likely to strike out.

The following chart shows strikeouts as a percentage of all 2-strike counts (2-strike SO%), in 2-year increments from 1988-2012. (The lighter-colored bars for 1990 and 1996 indicate a significant number of missing data; about 8%-10% of the PAs in those years are missing the ball/strike count, so those calculated percentages are less reliable.)

2S-SO Pct

 

But the rise in 2-strike SO% is only 15% since 1988. Where’s the rest of that 35% increase in overall K rate coming from?

Well, you can’t strike out until you get to 2 strikes. The frequency of 2-strike counts is the other major piece of the equation. Here are 2-strike counts as a percentage of all PAs (2-strike PA%):

2S-PA Pct

 

To my surprise, the 2-strike PA% has gone up more than the 2-strike SO%. From 1988-2012:

  • The 2-strike SO% rose 15% (from 34.7% to 39.8%).
  • The 2-strike PA% rose 20% (from 41.5% to 49.7%).

And the pace of change in these factors has been different. The 2-strike PA% has risen pretty steadily since 1988. But most of the rise in 2-strike SO% has come in the last 4 years. From 1988-2008, the net change in 2-strike SO% was less than 6%, with almost no net change from 1994 to 2008. But it’s risen more than 8% in the last 4 years.

If you have any thoughts on these data, you know what to do.

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18 Comments on "Soaring Strikeouts: It’s not just the 2-strike approach"

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Mike L
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Being a capitalist at heart (although a centrist Democrat) I look for market forces. Three trends happening at the same time, slightly asynchronous. The first is steroids-era revalued home run (new level is really established in 1996), the second is the money-ball grind it out stat-head driven take the walk strike out or hit it nine miles mentality (think the younger Jason Giambi) and the third, most recent one, is a combo of the intensified testing and changes to the structure of bullpens-larger number of pitchers and specialists throwing harder and harder. Management/players go for the money (literally and in… Read more »
Tim Pea
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Some very smart agent said to a player, “you can increase your HR rate by swinging with 2 strikes the same way you swing with none or one”. “See, shortening your swing with 2 strikes gets you a meek ground out, while swinging for the gates gets you a HR once in a while.”

Doug
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Good stuff, John. More two-strike counts indicates some combination of more patient hitters and making less contact early in the count. The fact that more strikeouts are resulting from those 2-strike counts is not surprising for the reasons you’ve indicated. With half of PAs now going to 2 strikes, it’s not surprising that: – games take so long to play – complete games are such a rarity – the 12-man pitching staff is now the norm instead of just 10 Here are the OPS numbers for all PAs and PAs after going to 2 strikes, and the change. – AL:… Read more »
no statistician but
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Is there any data on swinging vs. called strikes early in the count? Also foul balls vs missed swings? Probably not, but these things might add some insight into what’s happening.

Doug
Editor
Results for each count are on B-R under League Batting Splits. For example: http://www.baseball-reference.com/leagues/split.cgi?t=b&lg=NL&year=2012 Types of strikes are under League Pitches Batting. For example: http://www.baseball-reference.com/leagues/NL/2012-pitches-batting.shtml Here are percentage of pitches per PA, % of pitches that are strikes, and % of strikes looking, swing&miss, and in play for 1988/2012. ……..Pit/PA……% Strk……..% Look…….% SW&M…….% In Play – AL: 3.62/3.84…62%/63%…25%/28%…14%/16%…34%/30% – NL: 3.54/3.80…63%/64%…24%/28%…14%/16%…34%/29% Note that % of strikes that are fouled is basically unchanged. So, pitchers are basically throwing strikes and balls at about the same rate as 1988, but are having to throw more of them because batters are both taking… Read more »
no statistician but
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Doug:

Your last comment brought back something from my wasted youth: when I was playing league ball in the Fifties and Sixties, the Bronze Age, let’s say, taking a called third strike was one of the minor sins except when the count was full, and even then, if a pitch was close enough to the strike zone to to fool the ump, then you ought to have taken a cut at it.

Called out on strikes equalled humiliation.

mosc
Guest

I like this thought Doug. Free swinging is supposed to be a stat head thing but a stat head would understand the value of avoiding an out trumps everything else. You’d think stat focused baseball people would further stress free swinging without two strikes but continue to encourage people to shorten up with two strikes.

Tim Pea
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That’s not true Doug.

e pluribus munu
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John, When you write that we know what to do if we have thoughts on the data, it’s a little ambiguous: given my skills, I know I should shut up. Yet . . . What strikes me (sorry) reading the early replies from Mike, Doug, nsb, and mosc, is that the analysis is entirely focused on hitters. I’m sure the balance lies in that direction, but surely pitching staffs and coaches are not passive observers of batter behavior: I can’t help but wonder how pitcher adaptation to increased 2-Strike, K, HR rates may be contributing to the rate of change,… Read more »
Richard Chester
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It’s interesting to know that, in 2012 anyway, just about half of all PAs went to 2 strikes and the overall BA was just .178.

bstar
Guest

I would consider the re-introduction of the high strike in baseball (mandated by MLB in 1999 and reinforced with pitch f/x in 2006) and potential increasing fastball rates as part of the equation as well.

Although pitch speed may not be increasing that much, the average velocity of a fastball that a batter must face has almost surely risen, due to the increase of relievers pitching more innings and their increased strikeout rates vs. those of starters (as JA notes @10).

dj
Guest

This was a great post, John. Really got a lot of out it.

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