The Truth Behind the Rise of the Strikeout in Major League Baseball

Zachary D. Rymer@zachrymerMLB Lead WriterMarch 9, 2013

You may have noticed at some point within the last couple years that today's hitters in Major League Baseball just can't stop striking out.

Don't worry. It's not just you. There's an actual trend going on.

As Baseball-Reference.com's records can show, major league pitchers have been striking out more and more hitters every year since 2005. The per-game numbers look a little something like this.

  • 2005: 6.30
  • 2006: 6.52
  • 2007: 6.62
  • 2008: 6.77
  • 2009: 6.91
  • 2010: 7.06
  • 2011: 7.10 
  • 2012: 7.50

There you have it. Eight seasons, and one eyebrow-raising trend.

The strikeout totals from the last five seasons (2008-2012) are particularly alarming. Before 2008, there had never been a per-game strikeout rate as high as 6.77. That means that a new strikeout record has been set each year for five straight seasons now.

So...what exactly is going on?

A couple things, really. Let's take a look.

How Hitters Are Helping

With so many strikeouts happening these days, one's first instinct is to point an accusatory finger at the guys taking them. Clearly, something's gotten into hitters.

Actually, it may not be a matter of what's gotten into them so much as a matter of what's gotten out of them.

As ESPN's Jayson Stark noted last summer and I've written about in the past, offensive numbers have declined drastically ever since MLB first started testing for PEDs in 2005. Here's a quick look at how averages and slugging percentages have declined, courtesy of Baseball-Reference.com.

2005 .264 .419
2006 .269 .432
2007 .268 .423
2008 .264 .416
2009 .262 .418
2010 .257 .403
2011 .255 .399
2012 .255 .405

The fact that things really started going downhill in 2008 is significant. That was the year after the Mitchell Report was released, resulting in pretty much everyone in and around baseball going into panic mode. Offensive numbers immediately became less juicy, and they have yet to recover.

This alone doesn't explain the rise in strikeouts, mind you. Hitters and pitchers may be competing on a more even level now, thanks to the league's ongoing manhunt for Hulk-like sluggers, but it doesn't take muscles upon muscles to simply put the ball in play. PED testing is an explanation, not the explanation.

The increased aggressiveness of hitters is another factor. Hitters swing away more in today's game, a reality reflected by a couple of trends.

One is the fact that sacrifices have long since gone out of style. The number of sacrifice hits per game was in between 0.40 and 0.50 every year between 1957 and 1982. Sacrifices started to go out of style in 1983, and they have yet to come back in style.

Here are the numbers since 2005.

  • 2005: 0.33
  • 2006: 0.34
  • 2007: 0.32
  • 2008: 0.31
  • 2009: 0.34
  • 2010: 0.32
  • 2011: 0.34
  • 2012: 0.30

Not exactly a rising trend, to be sure, but a trend all the same. There are fewer sacrifices per game, and that means more hitters going up to the plate and taking their hacks.

Which would be fine, but hitters have picked up some odd plate-discipline habits in recent years. As tracked by Baseball Info Solutions and featured on FanGraphs, here are the O-Swing (the percentage of pitches a batter swings at outside the strike zone) and Z-Swing (percentage of pitches a batter swings at inside the strike zone) percentages from the last eight seasons.

Year O-Swing % Z-Swing %
2005 20.3 68.0
2006 23.5 66.6
2007 25.0 66.6
2008 25.4 65.4
2009 25.1 66.0
2010 29.3 64.4
2011 30.6 65.0
2012 30.8 64.7

Take a look at the O-Swing percentages, and you'll notice that hitters have taken to expanding the zone more in the last five seasons. You'll also notice that things have gotten particularly interesting in the last three years as strikeout totals have taken a big hike.

For one, hitters are swinging at far more pitches outside the strike zone. They're also swinging at fewer pitches inside the strike zone. This combination of chasing and taking is helping pitchers pile up more strikes, and more strikes are invariably going to lead to more strikeouts.

Of course, pitchers don't just need help from hitters in the strike department. They also need help from the umpires.

Sure enough, they're getting it.

How Umpires Are Helping

Life used to be simple for umpires. They made the calls, and it was hard to legitimately dispute their calls (not every argument with an umpire qualifies as a "legitimate" dispute, after all).

Not so much anymore. Starting with slow-motion replays and continuing on with strike-zone markers, advances in television technology have worked to erode the authority of umpires. Then came the PITCHf/x tracking system, which was in every major league stadium by 2008 and has been used to keep umpires on their toes.

"It's a grading tool, but we use it to help umpires improve," Peter Woodfork, then the senior vice president of baseball operations, told the Los Angeles Times in 2011.

Woodfork continued: "Umps don't always know where they're missing. If they're trending one way or another—say, they're missing the pitch down and away—they can see the data and make adjustments."

The damndest thing has happened since PITCHf/x burst onto the scene: Umpires are now calling more strikes.

Credit goes to Jeff Sullivan (whose work is always great) of FanGraphs for crunching the numbers and determining that umpires have gotten better at calling balls and strikes. He noticed that, for both starting pitchers and relievers, the number of pitches being taken inside the strike zone and called balls has gone down dramatically in the PITCHf/x era (which technically began in 2007). 

Evidently, the feedback umpires have gotten, thanks to the PITCHf/x system, has had an effect. Umpires aren't missing as many calls, and that's just another thing that's contributing to the theme that started cooking above: More strikes lead to more strikeouts.

Not that umpires have to be perfect to help pitchers out. Pitchers are still getting at least a few strikeouts per year, thanks to umpires' egos. 

We see it way more often than we should: a hitter taking what he figured was ball four, turning to head to first base, and then getting called out on a delayed strike-three call by the home-plate umpire. It's a sort of twitch that umpires have, and sometimes it results in them getting helmets thrown at them.

It's not a major contributor to the rising strikeout totals, to be sure, but it's a contributor all the same.

So we know that hitters are helping to contribute to the rise in strikeouts, and we know that umpires are doing their part as well.

But let's not kid ourselves. This is all about the pitchers.

Above All, How Pitchers Are Helping

A couple years ago in 2010, "The Year of the Pitcher" happened, and it was glorious.

Here's the thing, though: The Year of the Pitcher hasn't gone away. The 2010 season felt like a fluke at the time, but now we know that it was the start of a trend.

The league ERA was at 4.32 in 2008 and in 2009. Since then, it's gone: 4.08 in 2010, 3.94 in 2011 and 4.01 in 2012.

Not surprisingly, the decline of ERAs and the rise of strikeouts has to do with a rise in strikes. Sullivan crunched more numbers in that department and found that pitchers are throwing more first-pitch strikes, getting more 0-2 counts and generally throwing more strikes these days than in days past. The same old refrain applies: More strikes equal more strikeouts.

Of course, it gets more complicated—not to mention more fascinating.

The Stark article referenced above brought up several very good points about how pitchers are just plain different in this day and age. For one, pitchers are throwing harder fastballs than ever before. They're also throwing fewer fastballs than ever before.

Using Baseball Info Solutions data from FanGraphs, we can see that the numbers say it's all true.

Year Fastball % Avg. Fastball Velo
2005 61.9 90.1
2006 61.1 90.5
2007 60.6 90.3
2008 60.7 90.7
2009 59.7 91.2
2010 58.7 91.2
2011 57.8 91.5
2012 57.6 91.6

Stark proposed several theories for why fastball velocity has gone up, such as the use of long-tossing to build up arm strength and the careful crafting of hurlers while they're young.

A simpler theory is that pitchers are able to throw harder fastballs because they're throwing fewer of them. Maybe there's a tradeoff there.

But the desire for more velocity doesn't necessarily explain why pitchers are throwing fewer heaters. The more likely explanation is that pitchers are throwing fewer heaters because they've seen fit to adapt.

Philadelphia Phillies pitching coach Rich Dubee told Stark:

I just think pitchers are equipped more. They do different stuff with the pitches they have... I think it's because the strike zone shrunk. You didn't have the high strike. You didn't have the width (off the corners) of the plate. And I think because of that...guys became more creative.

Phillies legend Mike Schmidt told me something similar when I spoke to him last July, and he credits pitching coaches for being behind the change that's swept across baseball.

"Pitching coaches have now become pitching gurus," said Schmidt. "They’ve taken the time with pitching grips and pitching theory more so than they were in the past. Big, hard throwers now have nasty changeups to go along with the nasty sliders, forkballs and split-fingers. The pitching theory nowadays is to throw anything at any time. It’s not necessarily challenge every hitter when you get a 3-1 count or a 2-0 count."

It helps that pitching coaches and pitchers have so much data to turn to. Stark noted that there's more information available to men in uniform than ever before. If a pitching coach or a pitcher wants to know a hitter's tendencies, he can grab a sheet of paper that will tell him all about how a hitter covers the outside corner of the plate between 7:35 p.m. and 7:45 p.m., and so on.

Hitters also have more information, of course, but Texas Rangers hitting coach Dave Magadan explained why all the data is much more useful for pitchers than hitters:

If you're a pitcher, you see an immediate result. You know a guy's got a hole. So you hit that spot, you expose the hole, and you get an out. But if you're a hitter and you know the hole, you can get all the information you want. But it takes hours and hours of working on it, and hitting off the tee, and doing soft-toss, and gradually working your way to where either you lay off the pitch or you find out how to hit it.

And if it's a pitch in the strike zone, you'd better find out how to hit it, or you're going to have a short career. So to me, the pitcher has a big advantage there.

All of this speaks to the trends that have developed among hitters. It could be that they're taking more strikes because pitchers know where to attack them in the strike zone. Likewise, they could be chasing more pitches because pitchers known when to get them to chase.

And indeed, the fact that pitchers are throwing fewer and fewer fastballs borders on being unfair. They have all the data they need to attack hitters' weaknesses, and they're attacking these weaknesses with more weapons. And when they do throw fastballs, they've got more pepper on them than before.

I fear the worst, my friends. It seems that pitchers have become self-aware. They may be content with striking out more and more hitters for now, but eventually, they'll mobilize and set forth to destroy us all one strike at a time.

Flee. Flee for your lives.

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