A Look at Adam Wainwright's 2012 Season Through the Prism of DIPS

Last year, I bit the bullet and got bleacher seats for the St. Louis Cardinals' home opener. I wanted to see Clydesdales, Cardinal greats in red blazers, and Adam Wainwright. The day was a rainy one, so the Clydesdales didn't trot around the Busch Stadium warning track. Despite the bad weather, Stan Musial, Bob Gibson, Lou Brock, and Ozzie Smith road around, waving to the fans during a lull in the rainfall. Despite a delayed start, Wainwright took the ball for the home team and made his first start in St. Louis since undergoing Tommy John surgery.

The start did not go as scripted. The visiting Cubs shelled Wainwright. By the time manager Mike Matheny pulled Wainwright out of the game after just three innings, the righthander had given up eight earned runs on seven hits and two walks. Two of the seven Chicago hits were homers and one of those was a grand slam off the bat of rookie Brian LaHair that pushed the Cubs' lead to 8-0.

After the game, I attempted to reassure myself about Wainwright. I told myself it was only one start, that two-homer games happen, that it was cold and rainy. All of those things were true. But experiencing the shellacking firsthand made it stick with me throughout the season and all of the bad memories came rushing back during Wainwright's rough outing in Game 5 of the NLDS.

Last year was an up-and-down one for Wainwright. He finished 2012 with some stats that looked like they belonged to the pre-injury ace and others that didn't. Wainwright struck out batters at a healthy rate, issued walks about as often as we'd come to expect pre-sugery, and his home-run rate regressed to a somewhat normal figure by season's end. Despite those stats, though, Wainwright posted an ERA of 3.94 that sticks out like a sore thumb.

ADAM WAINWRIGHT STATS (2009, 2010, & 2012)

Wainwright went from two consecutive seasons of having one of the best ERAs in baseball, to Tommy John surgery and rehabilitation, to an about-average ERA. Here is how Wainwright's ERA has stacked up against the overall ERA for National League starting pitchers over his last three full seasons.

WAINWRIGHT VS. NL STARTERS (2009, 2010, & 2012)

In 2012, the gap between Wainwright and his starting pitcher peers closed in the area of run prevention. There is a series of pitching stats available at Fangraphs that are known as the "minus" stats. They take a pitching stat and adjust it for park effects. I like this stat because it shows that there is a difference between posting a 3.00 ERA while pitching with Coors Field as your home park and posting a 3.00 ERA while pitching your home games in San Diego. They also adjust for league scoring environment and are then adjusted so that 100 is average. The further below 100 a pitcher's "minus" stat, the better. The further above 100 a pitcher's "minus" stat, the worse it is. As the following chart shows, after adjusting for the pitcher-friendly park effects of Busch Stadium, Wainwright's 2012 ERA was actually slightly worse than average.

WAINWRIGHT'S ERA & ERA- (2009, 2010, & 2012)

*The Fangraphs Glossary primer on ERA- and the other "minus" stats can be found here.

A quibble sabermetricians have with ERA is that it is somewhat dependent on a pitcher's defense (and, for that matter, the official scorer). One of the more intriguing theories to come out of the sabermetric community is that of Defense Independent Pitching; or, DIPS. (SABR posted an excellent history of the DIPS theory over the weekend that is well worth a read.) The DIPS theory gave rise to metrics based on those events over which a pitcher's defense has no control. At Fangraphs, some of these metrics are readily available as Fielding Independent Pitching (FIP) and Expected Fielding Independent Pitching (xFIP). The Fangraphs Glossary entry for FIP explains the stat thusly:

Fielding Independent Pitching (FIP) measures what a player's ERA should have looked like over a given period, assuming that performance on balls in play and timing were league average.

The FIP formula is one that is calculated by giving weights to the following stats: home runs allowed, walks, hit batsmen, and strikeouts before dividing by innings pitched. The xFIP formula is similar to FIP but substitutes a league-average home runs rate for the pitcher's actual home run rate. If one goes by the fielding-independent metrics, Wainwright's 2012 was not at all concerning. In fact, it was quite good. Given the inputs, that's not surprising.

WAINWRIGHT FIELDING-INDEPENDENT STATS (2009, 2010, & 2012)

Looking at Wainwright's fielding-independent stats allows us to zero in on what plagued him in 2012. It wasn't fewer strikeouts or more walks. Rather, it was the fact that opposing batsmen had more success when they were able to put lumber to horsehide. The stats for hitters facing Wainwright corroborate this.

OPPOSING BATTERS VS. WAINWRIGHT (2009, 2010, & 2012)