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You get a dinger, and you get a dinger, and you get...

There’s been an explosion of home runs in MLB over the past year and a half and the trend has continued this season. What’s causing the increase in power?

Well, Mark McGwire, regarding your famous quote when you guest-starred on The Simpsons, today we’re going to do both. Except, we’re not just seeing a few dingers lately. More and more home runs are being hit over the past few years, to the point where some ballplayers are even suspecting that the ball is juiced.

I can’t blame them; after all, it’s not necessarily that pitchers have just forgotten how to pitch. Let’s take a look at a few stats that show how much power has increased.

Isolated power (slugging percentage minus batting average) has increased by about 10%, home runs per nine innings has increased by over 20%, and home runs per fly ball hit has increased by about 35%. I also included strikeouts which have increased by about 16% as well. Over the past decade, we have been seeing an amount of power that rivaled the Steroid Era as 1999-2001 all had a league ISO in the .160s and a HR/9 approaching 1.2 (FanGraphs doesn’t have data on HR/FB% for those years, however). The difference in the Steroid Era though was a lack of strikeouts as the K-rate was about 16%, which is a big reason why many felt the Steroid Era benefited the hitters.

There are a few reasons for the recent increase. First, pitchers are throwing harder and the strike zone became larger, which led to the increase in strikeouts. Because of their increasing frequency, hitters weren’t chastised as much and thus starting swinging harder instead of focusing on putting the ball in play. Additionally, hitters are realizing that a slight uppercut swing can do more damage than the level swing that has often been preached, which has led to not only more balls in the air but also more balls in play landing beyond the outfield fence. And of course, there’s the theory (which I somewhat believe) that the ball is juiced as MLB is looking to respond to the rapid increase of strikeouts. Hey, if it happened in Japan, it could certainly happen over here.

If it’s just a matter of hitters making adjustments league-wide, I wonder if MLB minds that home runs have increased significantly. Maybe not; after all, “chicks dig the long ball” is a phrase we’ve all heard. Combined with the focus on shrinking the strike zone this year, it’s possible that this trend will continue as hitters are allowed to become even more selective at the plate. I’m not sure if that’s good or bad for baseball, but one thing’s for sure: we’re watching this generation’s Mark McGwires sock more than just a few dingers.