Bill James measures the upward pressure on strikeouts (subscription required), and finds that there is no reason to believe strikeout rates won’t continue to increase:

Where are we now?

Well. . .it ain’t pretty. Since 2004 the Strikeout Push Effect has dropped slightly but steadily, down to a present figure of +1.47. In the years 2009 to 2011, high-strikeout hitters created 5.04 runs per 27 outs, while low-strikeout hitters created only 4.93 runs per 27 outs. On the other hand, high-strikeout pitchers allowed only 3.65 runs per 9 innings, while low-strikeout pitchers allowed 5.00.

I would have much preferred to find that the upward trend in strikeouts was leveling off. Unfortunately, that does not appear to be the case. High-strikeout pitchers in today’s game are dramatically more effective than low-strikeout pitchers, while high-strikeout batters are also somewhat more effective than low-strikeout batters. We are where we have always been, only worse. Strikeouts, in my opinion, will continue to go up.

Bill notes that strikeouts really took off in the last eight seasons. Most of that has to do with both high strikeout pitchers and batters being the most effective players, but I also wonder if part of it has to do with the theory of Defense Independent Pitching, credited to Voros McCracken. Once people realized why strikeout pitchers were so important, it would give them a solid reason to build around them.

By the way, the strikeout paradox of high being good on both sides of the ball is one of my favorite statistical anomalies in the game.