A fan of the Yankees, Red Sox, and large sample sizes.

 
WHEN HOMERUNS ARE HIT

Yesterday, John Lackey pitched a pretty good game, and hadn't surrendered any runs through 6 2/3 innings, at which point he was pulled in favor of Scot Shields after he loaded the bases. No problem, of course, since Brandon Inge was coming to the plate and Inge is one of the worst hitters in the American League (with apologies to Darin Erstad, Willie Harris, and quite a few others, actually). Of course, Inge proceeds to hit a grand slam, slamming Lackey with 3 ER. Still not a bad outing, and much better than Lackey's previous starts this year.

Tonight, Mulder hasn't been so hot, surrendering a bunch of hits and walks, before settling down and throwing a couple scoreless innings. He gave up a solo homerun to Jorge Posada, and was lucky Jorge didn't come to bat with men on base, like there had been most of the game. Mulder's outing would have been much worse had the HR come at a different time.

That got me thinking, are homeruns more likely to be hit at different game states? Most importantly, do more homeruns get hit without anyone on base? That makes a little sense - pitchers probably pay more attention to preventing homeruns when it will cost them more. Using Retrosheet data and ASS, here's a chart showing the probability of a homerun occuring at the different base states in the years 1972-1992 and 1999-2002:

basesit    hr      n        hr/n 

Loaded     2104  93587     .022 

2nd & 3rd  1286  88385     .015 

1st & 3rd  2801  139730    .020 

1st & 2nd  5980  293575    .020 

3rd        2202  125557    .018 

2nd        6407  373843    .017 

1st        16790 830747    .020 

Empty      50073 2213779   .023

Here's just 1999-2002 data:

basesit    hr      n       hr/n 

Loaded     574   19657     .029 

2nd & 3rd  357   17517     .020 

1st & 3rd  680   26211     .026 

1st & 2nd  1487  57621     .026 

3rd        516   22648     .023 

2nd        1535  69615     .022 

1st        4115  153707    .027 

Empty      12474 412260    .030

Looks like homeruns get hit more often with the bases empty, and not as much with runners in scoring position. Of course, once the bases get loaded, the rate increases again, probably because the pitcher has to throw strikes, or risk walking in a run. Of course, the reason might also be that the pitchers who allow a lot of baserunners are bad, and bad pitchers also give up homeruns.

What about if we consider the number of outs? Does the number of outs alone affect when homeruns get hit? Using 1999-2002 data:

outs  hr    n       hr/n 

   2 6845 253370    .027 

   1 6992 259401    .027 

   0 7901 266465    .030

Hmm, a small advantage to the hitter with no outs. I don't know why, or if it's significant. I wonder if there are any unique combinations of base/out states that are extreme cases either for or against the hitting of homeruns:

outs:basesit hr     n      hr/n 

2 1st        1427 53555    .027 

2 3rd        278  12337    .023 

2 Loaded     254  9102     .028 

2 1st & 2nd  609  25402    .024 

2 2nd        681  30675    .022 

2 1st & 3rd  320  12335    .026 

2 Empty      3116 102140   .031 

2 2nd & 3rd  160  7824     .020 

1 2nd        553  24389    .023 

1 1st & 3rd  236  9400     .025 

1 Empty      3626 128661   .028 

1 1st & 2nd  558  20669    .027 

1 3rd        195  8133     .024 

1 1st        1448  53731   .027 

1 Loaded     240  7471     .032 

1 2nd & 3rd  136  6947     .020 

0 3rd        43    2178    .020 

0 1st & 2nd  320  11550    .028 

0 2nd        301  14551    .021 

0 Loaded     80    3084    .026 

0 1st        1240 46421    .027 

0 1st & 3rd  124  4476     .028 

0 Empty      5732 181459   .032 

0 2nd & 3rd  61    2746    .022 

Nothing crazy, but with no outs and the bases empty, homeruns occur at the highest rate. Those are the lead-off plate appearances (or plate appearances following lead-off homeruns), so maybe pitchers are just a little rusty or don't quite have their focus starting an inning.

If anyone's got any other explanations, let me know.

Posted by Sky at 9:32 PM | 0 comments