Does late-season play translate into October success?

It is a common refrain that everything resets in the postseason. This is true strategically. Suddenly, in a sport with a 162-game regular season a single game becomes far more important than it was previously. Is it true with respect to player performance? While managers can make different choices in a tight playoff situation, players may not be as capable of adjusting simply because the consequences of the games have changed. Does the quality of a player's play from late in the regular season carry over into a player's postseason?

This is the first of two posts that examine this question. This post will look at it from the hitters' perspective. The second will then shift the focus to pitchers. To investigate whether or not late season play carries over into October I've taken wOBAs from the months of September and October from the regular season for the 2009 Yankees, 2008 Phillies and 2007 Red Sox. I then compare this to the wOBAs for those same teams' play in their respective postseasons. I've taken the last three World Series winners because they provide the largest sample of postseason data, and because it makes sense to look at winners. Their players played better. If October really does start everything over there will be no pattern carrying over from September in the regular season to the postseason.

Here's the data:

These data show several things. First, the 2009 Yankees played much better in September than the current vintage. Yankee fans knew that, but it's hard to ignore this when the data are right on the screen. Second, all of the World Series winners had three or four hitters heat up in October. Finally, the 2009 Yankees are a bit of an outlier when compared to the two champions that preceded them. They were much hotter to end the season, but that didn't transfer to the postseason as much as it did for the other teams. Aside from Derek Jeter, Hideki Matsui, and, of course, Alex Rodriguez, the Yankees mostly swung cold bats last October.

The data also show that October may really be a reset button. Across the board, September performance doesn't appear to be a strong predictor of playoff performance, for any of the three teams studied here. The 2009 Yankees are actually the best example of this. Seven of the team's nine everyday players had wOBAs above .380 in September last season. Only three hitters managed to keep that performance up in the playoffs. But the example holds for the 2008 Phillies and 2007 Red Sox as well. On the Phillies, only the September performance of Greg Dobbs and Chase Utley was a predictor for October performance, and even then it was a stretch for Utley. On the Red Sox, only David Ortiz, Jacoby Ellsbury and Dustin Pedroia saw their performances continue into October. Otherwise, September wasn't a strong predictor of October for most players on all three teams.

This is a bit of a silver lining for the Yankees. The data don't suggest that the Yankees' recent atrocious play will carry over into October. Every silver lining has a cloud, however. In our case that cloud is the fact that the Yankees have been losing because of their pitching, not their hitting. As Friday's 10-8 loss to the Red Sox proves, the offense can only be as good as the pitching allows it to be. And the Yankee pitching has been bad. Tomorrow I'll take a look at whether or not the teams' pitching numbers in September were a portent for what happened in October.