To add some perspective to the overall rise of the strikeout, let's make a quick switch to the conversation and move from K/9 to the total percentage of plays that end with a strikeout.
That done, this year pitchers are striking out batters 18.4 percent of the time, slightly lower than last year's 18.6 percent, but in the same vicinity, and that's consistent with the steady increase in strikeouts we've seen over the past 30 years. For the sake of comparison, in 1980 batters were being struck out 12.7 percent of the time, which represents an inflation rate for strikeouts of a little more than 46 percent over three decades.
Just in case you've got the Year of the Pitcher, 1968, up on a pedestal (or a higher mound), for the sake of comparison you'll find that was when batters were striking out 16 percent of the time. Not shabby, but that's a clip major league hitters shot past in the early '90s without looking back. Of course, not even lowering the mound had a critical impact on MLB's overall strikeout rates -- it took adopting the DH in 1973 to really bring it down to where it was in 1980.
Heck, thanks to the power of Baseball-Reference.com, let's run this as a little quick and dirty table, moving through five-year increments starting in 1980 on up to last year, with 1968 and 2011 tacked on for good measure. K% is self-explanatory, while BIP% is the rate of balls in play; Mr. Average is an example of an ERA title qualifier whose K% was around MLB-average that year.
The result: Strikeouts? Up, up, up. Balls in play? Not too coincidentally, down, down, down.
I won’t pretend to claim exactitude in my selections of “Mr. Average,” since I went for people with name recognition close to the MLB-average strikeout rate. That said, I don’t think I’d be hazarding all that shocking a guess if I suggested that the guys at the end of this table throw harder than the guys at the beginning.
Having thrown all this out there, there are three additional areas worth touching on: The changes in how often you'll see pitcher's counts and how often then wind up a strikeout, the changing use of bullpens and relievers, and the impact of what all these strikeouts mean in terms of balls in play and particularly in terms of defense.
The count: It shouldn't surprise you at all that in comparing data from 1990 and 2011, symptomatic of the rise of strikeouts, we're seeing more at-bats reach pitcher's counts (0-2, 1-2, but also 2-2 and 3-2), and hitters are striking out more frequently once they get into these counts (generally about 2-3 percent more often). Call that a reflection in the change of approach, or of better pitchers, or umpires reading those memos about speeding up games, or perhaps all of these things and more, but it's a day-to-day fact of life for big league hitters that they're more likely to get behind, and more likely to whiff once they get there.
Relievers: This goes back to something I wrote a couple of weeks ago about how, in today's lower-scoring environment, starters are pitching later into their ballgames, which in turn creates fewer possible plate appearances and outs for relievers. With teams nevertheless still carrying seven relievers per pen on average, one way of looking at it is that this means fewer things for them to do, but the other is that it becomes that much easier for a manager to secure the platoon advantage on defense, or get an advantageous batter/pitcher matchup in general.
As a result, it really shouldn't be all that surprising that relievers these days are striking out batters 20 percent of the time on average, or about as often as Nolan Ryan was striking people out when he pitched in 1980. But it's every day for every team, for roughly a third of every ballgame, and that's before we get to today's truly spectacular nothing-in-play people like the Cubs' Carlos Marmol.
One interesting thing to note: In 1968, the reliever strikeout rate was lower than that of starting pitchers, something you just don’t see any more, and won’t.
Defense: After the Rays put their Devil in his hell in 2008 and flipped from baseball's worst defense to one of its best, it became fashionable in sabermetric circles to talk a lot about the new importance of defense. Now, in the broad strokes, sure, you didn't want to field what very well might have been baseball's worst defense ever, as the 2007 D-Rays had been while enduring a modern-record worst Defensive Efficiency (.652).
However, nowadays balls in play per game are happening a lot less often, and Defensive Efficiency marks these days are still worse overall than they were in 1980, when a higher volume of plays had to be made in the field, because people weren't being struck out. Thirty years ago, 76 percent of all plate appearances ended with a ball in play; that dropped to 70 percent in the '90s, and it's below that at 69 percent today. To put it another way, thirty years ago the teams you'd see in a game were fielding almost six more balls in play per game than you'll see from your seats today. Where did those plays go? You already know -- they're happening at home plate.
So where does defense come in? Well, think about it: More strikeouts means more time spent with guys standing around in the field watching all the whiffery. It means that not only is there less chance that a ball in play is going to happen in the first place, there's that much less possibility that ball is going to get hit in the general direction of one of the lowest-percentage spots on the field, like the outfield corners -- or where guys like Lance Berkman happen to be parked these days.
Christina Kahrl covers baseball for ESPN.com. You can follow her on Twitter.