Lance Berkman and Plate Discipline Stats

I can't believe I'm about to say this, but I think Richard Justice might have just had a good idea.  In today's column, he writes about how Lance Berkman is struggling out of the gate this season and wonders what's up, particularly since his strikeout totals are so high.  But specifically, he wonders if Lance has decided to put the team on his back and is "expanding the strike zone" by swinging at stuff that's actually outside the zone, thus making it easier for opposing pitchers to get him out. 

Well Dickie J., there's a tool for that.  I'll explain after the jump.

Fangraphs keeps a set of statistics on plate discipline, keeping track of how often players do some of the following things:

• How often a pitch is thrown in the strike zone (Zone%)
  
• Swing at a pitch (Swing%)
  
• Swing at balls inside the strike zone (Z-swing%)
• Swing at balls outside the strike zone (O-swing%)
• Makes contact with a pitch that he swings at(Contact%)
• Makes contact with a pitch inside the zone that he swings at (Z-Contact%)
• Makes contact with a pitch outside the zone that he swings at (O-Contact%)

So Justice is speculating that Berkman is "expanding his zone" allowing pitchers to strike him out more easily.  If this were the case, we'd expect to see his O-swing% to be higher than normal, and perhaps his Zone% to be lower, reflecting a tendency of Lance to swing at more outside pitches and a tendency of pitchers to try to strike him out with outside stuff. We'd probably also expect to see his Swing% go up too, if he were pressing in the way that Justice suggests.  Since fangraphs provides these numbers, we don't have to speculate. Here's Lance's rates from 2007 onward:

So it looks like Lance is swinging the bat about less than normal, by about 3%, which doesn't match up with the hypothesis that he's pressing.  On the other hand, he's getting about 1-2% fewer pitches in his strike zone than normal, and he's swinging at pitches outside the zone by about 1-2% more often than normal.  I'm not sure that this explains Lance's early season woes, however...at this point, a difference of 1% is only going to amount to about 3 pitches,which shouldn't be the difference between last year's .986 OPS and this year's .757 OPS.  So it looks like Justice is wrong in this instance.  But I'm totally willing to give him credit for trying.

The other plate discipline stats that fangraphs keeps seem to suggest that the reason is even simpler than Justice had speculated.  Berkman's just not making contact. 

That's quite a drop off!  He's making about 10% less contact overall.  That amounts to an extra swing-and-a-miss every 5 plate appearances, which is about once a game...this could account for a significant portion of Berkman's power outage, but it shouldn't account for all of it.

So what else is there.  My personal theory is that his bout with biceps tendonitis at the beginning of the season set his preparation back a little bit and he's yet to hit his stride. 

But it's also entirely possible that he's not making very good contact with the pitches he's hitting.  Lance is seeing significantly more sliders this season than he has in any previous season, and these may end up being weak grounders, as evidenced by a reduced number of line drives.  Also, he's had some rotten luck when he puts the ball in play, as seen in his batting average when putting the ball in play (BABIP):

Hopefully, some combination of time in the batting cages to improve his contact rate, plus some better luck with where the balls are being hit will help Lance break out of his funk.

So there you go.  A nice analytical article (with the usual sample size caveats) inspired by Richard Justice, even though he was wrong.