This morning, Tom Verducci wrote a story at Sports Illustrated suggesting that perhaps Major League Baseball should consider some kind of "illegal defense" rule to reduce the effects of shifting, which has grown significantly in popularity over the last few years. In the article, Verducci notes that shifting has disproportionately hurt left-handed hitters, and is part of why offense is down so much over the last few years.
The rate of hits on balls that defenders could theoretically turn into outs is about the same now as it was for most of the 1990s, when home runs were plentiful and every team could score five runs per game. In fact, as shifts have become more prevalent over the last few years, the overall rate of hits on balls in play has gone up, not down.
Offense isn’t down across Major League Baseball because fewer in-play balls are getting past defenders. Offense is down in Major League Baseball because the league average strikeout rate is 20.3 percent, the highest it has ever been. If we want to change some part of the game to bring offense back to baseball, the strike zone is the first place to start.