Wednesday, August 09, 2006

the teenwolf effect

Long time readers of this site will recall that Craig Biggio is hit by a pitch more frequently on nights, like tonight, when the moon is full. He hasn't been hit during a full moon since June 22 of last season (when Jason Jennings hit him twice), but he still gets hit about 31% more often per game and 37% more often per plate appearance on the date of a full moon than he does during the rest of the lunar cycle. He records an HBP once every 7.33 games and once every 31.1 plate appearances when the moon is full, and once per 9.62 games and once per 42.6 plate appearances when it is not.
Well, it turns out this is not a local phenomenon. League wide, batters are hit 5.9% more often per plate appearance when the moon is full. About 1 batter per 120.3 is hit during full moons while non-full moon plunks occur about once every 127.4 plate appearances.
However, Biggio's increased batting average is not mirrored in league wide stats. Biggio bats .298 when the moon is full and .284 the rest of the time. He also increases his home run output from 1 per 43 plate appearance to 1 per 37 plate appearances. The major leagues as a whole, from 1988-2005, have the nearly the same batting average whether the moon is full or not - .2637 on non-full moons to .2635 on full moons. There is a slight increase in home run production during full moons, from 1.97 per game to 2.00 per game.

I have no explanation for this increase in hit batters during the full moon, but it is clearly an important area which should receive further study, and it would be the perfect opportunity for that collaboration between NASA and Major League Baseball that both groups have been waiting for. It's only fitting that the Astros should be at the forefront of such an effort.



At 8/09/2006 07:40:00 PM, Anonymous Mike in PDX said...

Well, if batters had been hit more frequently during new moons or crescent moons, it might suggest that they can't see the pitches as well. But since it's the other way around, maybe it means that pitchers can see their targets bettter.

At 8/10/2006 08:45:00 AM, Blogger pbr said...

Someday I should see if the reverse is true on dates of the new moon, but I was sort of hoping that someone with more experience in astronomy would pick up my work and run with it. Or something. It'll be interesting to see how it effects HBPs when that email about Mars comes true - you know, the one that keeps going around claiming Mars is going to be so close to earth than people in Denver will have to walk stooped over to avoid hitting their heads on it? That should be interesting.

At 8/10/2006 10:48:00 AM, Anonymous DM said...

pbr, I hate to tell ya this, but hoping for somebody to pick up your work and run with it can I put this politely? Unlikely. Your dedication to the fine art of statistical massage is unique. Truly.

Which is why you are the only person on earth who can tell me if batters are more or less likely (on a per at-bat basis) to be hit by a pitch in an indoor stadium.

At 8/10/2006 11:43:00 AM, Anonymous Dave said...

If I had to guess, based on the data here I'd say that the increased HBP activity had something to do with werewolves. There's no other correlation I can think of.

At 8/10/2006 12:42:00 PM, Blogger pbr said...

Clearly it's werewolves. I should probably dig up the rosters of the old London Werewolves of the Frontier League, see if any of them made it to the majors, and check on their full moon stats.

I can't believe that team couldn't support itself just on merchandise sales.


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