Another Double in the Wall

Fenway's Green Monster both helps and hurts batters.  Kevin Youkilis provides a great example of why that is.  Look at the distribution of Kevin's doubles and homers at home over the previous three seasons:

Kevin Youkilis, doubles and home runs at Fenway Park, 2008-2010.His line of doubles draws out the position of the wall, with most of his home runs landing in the seats above.

On the road, the doubles to straight away leftfield disappear.

Kevin Youkilis, doubles and home runs on the road, 2008-2010.Fenway turns home runs into doubles, but some outs into doubles as well.  In this time frame, Youkilis hit 57 doubles and 39 home runs at home, 38 doubles and 36 homers on the road.  None of his home runs at Fenway were line drives, however, while six of his road shots went out on a line.  He loses a few line drive shots playing in Fenway, but his greater double power more than makes up for it.

Dustin Pedroia and His Wall

Reader Jeff asked us to take a look at Dustin Pedroia.  Here's a quick look at some of his Home/Road splits over the last three seasons.

Dustin Pedroia

You can see that Pedroia's power zones are slightly diminished on the road.  As a righty at Fenway, he's made good use of the left field wall.  It's no secret that the green monster often turns what would normally be a fly ball out in most other parks, into a base hit.  While he's hit fewer HRs at home than on the road in the last three seasons, he's produced far more doubles at Fenway (108 to 61 in his career). 

Fly balls are converted into outs more often than any other type of hit ball (other than pop ups, of course).  Since 2008, Pedroia has hit 43 fly ball doubles at home compared to 13 on the road; the majority of those Fenway doubles have come on balls hit off the wall in left.  He also has a 2.8% lower line drive rate at home than on the road (16.9% to 19.7%).  This is a little less than two sigma, so it's not really a sign of any substantive change.  Still, I wouldn't be surprised if Pedroia has made an effort to put the ball in the air to left more at home knowing that he has a better chance of getting a hit, thus resulting in fewer line drives.

Trevor Cahill's Sinker: Luck or Skill?

Trevor Cahill had a fantastic year for the Oakland A's in 2010.  He was very successful in keeping the ball down, as he went from a 96 ERA+ in 2009 to a 136 ERA+ last season.  Some have noted that his very low overall BABIP (.237) is partially responsible for his success, rather than any particular ability to induce weak ground balls.  However, a closer look possibly indicates that luck may not have played as big a role in Cahill's success.

Cahill was one of the most successful ground ball pitchers in the majors; 56% of batted balls off his pitches ended up on the ground in 2010, 5th highest in the majors.  As you can see from the heat map above, he became very efficient at keeping his pitches down last season.  His GB/FB ratio went from .92 to 1.32 in one year.  The main reason: his excellent sinker.

Cahill's 2010 sinker was flat out nasty, averaging 14.8 feet per second of downward movement, putting him in the top 10 percent of sinkerballers.  This makes it tougher to chalk up his basement low .153 batting average on ground balls (best in the majors) to mostly luck.  He's obviously benefitting greatly from the movement he's getting on his sinker. If batters are finding it harder to makes solid contact as a result of that increased movement, it's possible they are hitting weaker ground balls; in turn, this would make it easier for his defense to field and turn these ground balls into outs. 

This is not to say that we won't see some regression this year.  It's certainly possible that a good chunk of these ground balls were simply finding infielders, particularly when well hit. But if he can keep his pitches down and moving as they did last year, don't be surprised if his overall BABIP remains in the cellar.