Power Imbalance, Part II

Following up on a point from last week – on the whole, home runs are down in both leagues this year, but far more dramatically in the AL, to the point where NL hitters are going yard more frequently than their AL counterparts for the first time in this decade. Of course, as the following chart shows, when you take out NL pitchers and AL DHs, the NL’s power output has been ahead all along, but is dramatically further ahead this season:

Year AL-AB AL-HR AL-DH-AB AL-DH-HR NL-AB NL-HR NL-P-AB NL-P-HR AL-HR/600 NL-HR/600 AL-w/oDH NL-w/oP
2007 73752 2120 7640 298 84208 2550 4505 26 17.2 18.2 16.5 19.0
2006 78497 2546 8035 392 88844 2840 4832 29 19.5 19.2 18.3 20.1
2005 78215 2437 8099 327 88120 2580 5025 18 18.7 17.6 18.1 18.5
2004 78731 2605 8146 328 88622 2846 4932 24 19.9 19.3 19.4 20.2
2003 78311 2499 8094 327 88426 2708 4981 29 19.1 18.4 18.6 19.3
2002 77788 2464 8159 316 87794 2595 4939 27 19.0 17.7 18.5 18.6
2001 78134 2506 8137 337 88100 2952 5007 26 19.2 20.1 18.6 21.1
2000 78547 2688 8178 352 88743 3005 5177 32 20.5 20.3 19.9 21.3

The last four columns are expressed in terms of home runs per 600 at bat. Of course, you could slice the numbers more finely if you had time, to take out the small number of AL pitcher and NL DH at bats and correct for Coors Field, but what’s interesting to me is the dramatic change in one season in the AL, much more dramatic than in the NL. I’ll leave you for now with the data but I may do a little more thinking about whether there is a plausible cause here beyond random variation.

2 thoughts on “Power Imbalance, Part II”

  1. It is also possible that NL pitching is simply worse right now. It would be interesting to check the HR rate in interleague play. It is interesting how much of the VORP leaderboard by position is NL dominated on the hitting side (i.e. this is more than a HR effect). Look at shortstop – long the AL glory position, now dominated by Ramierez, Rollins, Reyes, and so on.

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