Jon Rauch leans on slider for his early success

Throughout the offseason I complained often about the Jon Rauch signing, suggesting that the $3.5 million the Mets spent on the reliever could have been better used elsewhere. However, like many of his teammates, Rauch is off to a good start in 2012. After pitching a scoreless inning in Saturday’s win over the Phillies, he’s appeared in five of the team’s eight games and he has yet to give up a run. So, let’s look at Rauch’s start and see how he’s accomplished this and how likely he is to keep it up.

As you might expect from a reliever with a 0.00 ERA, Rauch has not given up a home run. Of course, it’s impossible to allow a homer when you have yet to surrender your first hit. In fact, Rauch has faced 18 batters and retired 17 of them, allowing only a walk to Steve Lombardozzi when he pitched two innings against the Nationals and picked up the win.

The secret to Rauch’s success in the early going is his 46.2 ground ball percentage, which would easily be a personal-best. His lifetime mark in the category is 33.8% and last year he had a 34.5 percent rate. As you might expect with such a dramatic change in results, Rauch is using a different mix of pitches here in the early going.

Last year Rauch threw his fastball 58 percent of the time. Here in 2012, he’s thrown his heater just 30.9 percent of the time. Now his main pitch is his slider. After throwing sliders 23.9 percent of the time in 2011, that number is up to 58.2 percent in 2012. It’s easy to see why Rauch made the change. After averaging 92.0 mph with his fastball in 2008, Rauch’s velocity has been on a steady decline. This year his average fastball velocity is at 88.5, a full mile below last year’s number.

Meanwhile, the slider was easily his most effective pitch in 2011, with a 0.76 wSL/C. By comparison, his fastball checked in with a -0.99 mark per 100 pitches. And early results with his slider are exponentially better in 2012, as he has a wSL/C of 6.56.

Rauch is one of just seven relievers to throw a slider at least 50 percent of the time here in 2012. His 58.2 percent ranks as the third-highest, behind Rafael Perez and Brad Lidge. Last year, only three relievers threw a slider 50 percent of the time – Carlos Marmol, Perez and Luke Gregorson. Interestingly, Marmol and Perez checked in last year with a 0.8 fWAR while Gregorson had a 0.2 mark.

This is not meant to imply that those who throw sliders a disproportionate amount of time cannot be effective. We only have to look at Marmol in 2010, who posted a 3.0 fWAR while throwing his slider 59 percent of the time. However, in that season, Marmol’s fastball has an average velocity of 94.1, compared to his 91.8 average in 2011.

It seems like Rauch is enjoying the switch in leagues, pitching in the National League for the first time since the first half of 2008. He’s also enjoying the benefits of his new mix of pitches, which seemingly has batters doubly confused. If you come to the plate expecting a mediocre fastball and instead get a better-than-average slider, it could be a tough adjustment for a batter to make.

To me it seems somewhat akin to Mike Pelfrey adding a split-finger pitch to his arsenal in 2010. In April, it caught batters completely off guard but they soon adjusted and by the end of the year it was a below-average offering. It’s not exactly the same, because the slider is not a new pitch and Rauch has had success with it in the past. But word will get out and batters will come to the plate expecting to see more sliders than fastballs when Rauch takes the hill.

I am thrilled that Rauch is having such great success for the Mets and I want nothing better than to see it last all year long. But at some point Rauch is going to start giving up hits and his lack of velocity and lack of a strikeout pitch is going to hurt him. In 2008, Rauch had an 8.29 K/9 ratio and this year he has a 4.76 mark.

While Rauch has a shiny 0.00 ERA, his peripherals tell a different story. His xFIP checks in at 3.56, giving an indication of how lucky he’s been so far. But after last year’s 4.86 ERA, I would gladly sign up for a 3.56 ERA from Rauch in 2012.

Right now Sandy Alderson looks like a genius for signing Rauch and the detractors (aka: me) have egg on their face. This is a case where I am more than happy to be wrong. However, I still expect regression to kick in and it would not surprise me to see Rauch post numbers like he did in either last year or 2009, when he had an xFIP in the 4.56 neighborhood.

If his peripherals end up in that range, Rauch can still be an effective pitcher if he maxes out in the luck categories, like 2009 when he ended up with a 3.60 ERA. But it can easily go the other way, like in 2011 when he finished the year with a 4.85 ERA. Perhaps the additional sliders will lead to fewer fly balls and home runs allowed than last year. Stranger things have happened and we at least have a reason to be optimistic about Rauch now, which we did not have back when he signed.