Ervin Santana's Trouble with the Long Ball

I originally had an idea to write about a pitcher who was giving up a ton of home runs this year, despite pitching in a home run-suppressing environment. For example, an arbitrary San Diego Padres or Seattle Mariners' starter who had an extremely high home-run-rate. But the more I thought about it, the more I realized that I had to write about the Los Angeles Angels' starter, Ervin Santana.

Santana currently holds the highest home run-rate (HR/9) of any qualified starter in baseball; he's given up 1.84 home runs per innings (or 1.21 per start). He also pitches in Angel Stadium; which is in no way a home run haven like Chase Field, Coors Field or Great American Ball Park.

According to ESPN: Angel Stadium is the fifth-hardest stadium to hit a home run in, this season. Since 2010, Angel Stadium ranks as the sixth most difficult to hit a ball out of. Since 2009, FanGraphs has consistently rated Angel Stadium's home run factor as 97; which means the stadium suppresses home runs slightly.

So how has a pitcher whose home park is Angel Stadium given up the most home runs, so far this season?

• 13 of the 29 (45 percent) home runs he's given up have come at home; thus, the other 16 were given up on the road.
• He's pitched one and two thirds more innings on the road than at home.
• Four of those 16 road homers (25 percent) were hit in Tropicana Field, a stadium that suppress home runs just as much as Angel Stadium.

Santana clearly is having trouble with home runs, and it's also pretty clear that it hasn't been the fault of the ballpark. HR/FB rates do fluctuate, and Santana's 19 percent home run to fly ball rate is absurdly high and well above his career average, 10.6 percent. So you could make the case that Santana has been unlucky, but I'm think that argument is only good to a certain extent.

Suppressing home runs is critical to Santana's success. It's critical because Santana has been a fly ball pitcher for almost the entirety of his career; his career GB/FB is 0.94. What is interesting this season, is Santana has induced more ground balls than ever before (47.3 percent), but this fact may be hurting him. Matt Swartz has argued that fly ball pitchers are better at inducing fly balls that don't end up in the seats, but unfortunately for Santana he hasn't been a fly ball pitcher this year.

Santana has had trouble with the home run ball before. In 2007 and 2009, two seasons that seem eerily similar to this one for Santana (he's been awful this year and he was awful in '07 and '09), his HR/9's were well above one (1.56 and 1.55, respectively). It's very difficult to be an effective starter with a home run rate above one.

We have Pitch F/X data from 2007 on, and in every year his fastball has ranked below average, based on linear weights. The velocity of his fastball is slightly down this year, and it's been bad again, but his slider has always been his best and most important pitch. Santana's slider ranked as the best in baseball (among starters) in 2011 and was a top-5 pitch, in 2008. HIs slider has been worse than ever this year; which, of course is a big problem for Ervin.

During the Pitch F/X era, Santana has had three season in which he's been very good (2008, '10 and '11), and three seasons where he has been horrendous (2007, '09 and now '12). HIs slider wasn't nearly as good in the bad seasons, especially '07 and this year. Santana cannot succeed without it working.

13 of the 29 (45 percent) home runs he's given up have come off his slider, a pitch he throws nearly 35 percent of the time. The pitch has resulted in a home run well over one percent of the time (1.6%, which is well above his career average 0.74%).

Santana generally gets a ton of swings and misses on his slider. Since 2007, he has a 17.79 percent whiff rate on the pitch. This season, his slider whiff rate sits at 17.45 percent; which obviously is a negligible difference.

But that average includes his rough 2007 and '09 seasons, where his slider whiff rate was also below average. Here is the difference between his whiffs in strikeouts in seasons where he performed well ("Good Ervin") and the seasons he did not ("Bad Ervin"):

The problem for Ervin hasn't been the speed or movement of the pitch, but instead his location. BrooksBaseball and Baseball Prospectus provide nifty graphs, that show us the location of just about everything a pitcher throws. This is the graph of where Santana' sliders which have resulted in home runs have been located, this season. He's left sliders up and over the plate; obviously those are the pitches that leave the ball park.

Santana throws his slider significantly more to right-handed hitters than he does to lefties, and the pitch is effective when he throws it down and away, off the plate to righties. Over his career he has done well to locate the pitch there, but this year his slider isn't ending up there nearly as often.

The Angels' rotation hasn't lived up to expectations, we all know that. People have been writing about their less than typical performances all over the place. But, a resurgence in their rotation is key to their chances of making the postseason (yes, they still have a shot). Many of made the argument that Dan Haren is the main issue, and that if Haren figures it out, the rotation will be much better, but for me I think the resurgence has to start with Santana's slider.

Ervin had a good start this week, in Boston. He went 6.1 innings, while giving up two runs, two walks and striking out four batters. He did give up a home run, but it came on a four-seam fastball and not his slider. His slider wasn't very good though, it had less movement than normal and produced a below-average number of whiffs (5 on 36 sliders). It's surprising that Santana was able to have success when his slider wasn't really working.

But it'll be more interesting to see if Santana can get his slider going again, give up fewer home runs, and give the Angels a shot at making the postseason.

Pitch Type Linear Weights was provided by FanGraphs, all other Pitch F/X data came courtesy of Brooks Baseball.

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