Understanding Slumps and Hot Streaks

Dave Cameron of USS Mariner and Fangraphs.com has posted an article that should be must reading for fantasy owners. He shows how to use BABIP and explains regression to the mean. If you have had trouble understanding these concepts or would just like to understand a little better, I recommend you read this article.

Explaining Away Regression To The Mean

Odds are you’ve read a story lately about how Russell Branyan is struggling as he reaches the summer of his first season as a full-time player. After a monstrous first half, he’s not hitting as well lately, and the explanations are pouring in. He’s tired. His back hurts. Pitchers are figuring him out. Managers have figured out how to shift against him and he hasn’t adjusted. If you’re looking for a reason for Branyan’s struggles, you have a buffet of choices to blame them on.

Of course, there’s a simpler explanation – it’s just natural regression to the mean.

In April, Branyan posted a .405 batting average on balls in play. In May, it was .391. These are outrageously high totals that nobody in history has been able to sustain, much less a first baseman whose hardest hit balls end up in the seats. There was basically no chance that he’d be able to continue getting balls in play to find a hole 39% of the time. We talked about this quite a bit, warning that regression was coming. A guy who strikes out as much as Branyan does can’t hit .300. It’s almost impossible.