Hafner 24/24

I've been curious, and secretly a little terrified, of Hafner's slump and wanted to look at his numbers a little more closely.  I'm not an expert on anything baseball, so this is really just a dumb compilation of numbers, but here they are anyway.  Hopefully Hafner's last two games reflect a return to form and this is all unnecessary anyway, but just in case...

Hafner's good and bad stretches this season conveniently break down into two 24 game stretches, April 2-May 2 (the good) and May 3-May 28 (the bad).  Here are his numbers for those two periods.

April 2nd to May 2nd

&nbsp24 113 86 17 29 3  0  6   19   24   9  23   2    0    1   3  .337 .487 .581

From May 3rd through May 28th

24 108 84 14 15 1    1   3  14  20  1   21   1     0     2  1 .179 .336 .321

What's the same and what's different?  His plate discipline is nearly identical across the two stretches.  His isolated discipline is .150 for the first 24 games and .157 for the second stretch with a pretty equal BB/K ratio, BB% and K%.  Unlike Peralta, Hafner's troubles don't seem to have any problem with seeing the ball.  What is dramatically different is his batting average and power across the two samples.  His BABIP dips from a probably inflated .403 over the first stretch (last year his BABIP was about .315), to .200 in the second stretch.  His ISO power dips from .244 to .142 (both down from the .304 he's averaged across the past 3 seasons).  His monstrous OPS in the first stretch was driven more by his .487 OBP than the donkey-strength we've come to know and love from Pronk.  The cold stretch has just been an acutely bad power outage on top of an already slow start (by Pronk standards).

So if his eyesight is fine but his power is off, what's the cause?  Some of the BABIP fluctuation is surely luck and sampling effects, but maybe we can identify something of more interest.  The good people at FanGraphs let us see the ball-in-play (BIP) data for each game.  Again looking at the first 24 games of Hafner's season and the second 24, we can look at his GB%, FB%, and LD%.  Through the first 24 games, Hafner was hitting about 30% of his BIP in the air, 48% on the ground, and 22% line drives.  In 2006, Hafner his 40%/39%/21%, respectively.  So already he was hitting fewer fly balls and more ground balls than last year, perhaps explaining his reduced power production.  Over the recent 24 game stretch, his BIP numbers shifted to 34%/51%/15%, an even pronounced reduction in fly-balls and also line-drives.  His HR/FB% was a very robust 31% during the first 24 games (he was just over 30% last season), but dipped to just under 14% over the second 24 games.  This might suggest, together with the decreased in BABIP and LD% that he's not hitting the ball as hard or as far.  Since his plate discipline hasn't dropped, I think it's hard to say he's not making good contact.  One last way to look at this is to compare his hit spray charts at from this season to last.  I can't break these up into his "good" and "bad" stretches, but if you compare his hits at Jacobs Field it does seem like he's not getting around and pulling the ball nearly as well as he did last season.  He's only got 4 hits to RF at home this year, 2 HRs and 2 singles.

So what does this all mean?  One possibility and probably one we should hope for is just bad luck.  Most of these numbers I've thrown out are all subject to significant small sample size caveats.  Hopefully these last two games show his luck changing.  However, for those who have watched him at the plate, I think it seems like something more substantive is at play.  Another possibility is that his swing is screwed up and that his decrease in fly balls (and power) represents a mechanical shift in his swing that can be fixed.  I'm in no way qualified to say whether that is plausible.  Another, and perhaps the worst possibility, is that he's playing through some sort of injury.  We all remember Hafner playing more in the field during spring training and talking about playing 1B once a week during the season.  During the first 21 games, through April 28th, Hafner played exactly 0 games at 1B.  This is of course partly due to Victor, Blake and Garko and their production.  But maybe it's also because he tweaked his elbow during the Spring (like he has done just about every time he's played the field in the past) and didn't feel comfortable taking the field.  It's worth noting that his first appearance at 1B, April 29th against Baltimore, is pretty close to the beginning of his really bad slump.  I think it's a real possibility that Hafner's loss of power, change in BIP percentages, and observed inability to hit those outside pitches represents a compensation for an injury...perhaps to his troublesome elbow (or alternatively the wrist he broke last season).

Again, I'm in no way anything more than a guy with internet access and the patience to dig up these numbers...but I think it's clear that Hafner has not really been Pronk all season and that the recent bad stretch just represents a more acute manifestation of what he has been suffering from all season.

Update [2007-5-31 17:50:0 by APV]: FoxSports provides batting average by pitch location data which confirms what we all suspect...Hafner has struggled with pitches low and away. But he's also struggled on high and inside pitches as well.

[editor's note, by Ryan]: Bumped to the front page.

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