For years pitchers have been evaluated based upon their win-loss record. More advanced mainstream metrics include ERA and WHIP. None of those tell the whole story about a pitcher though; win-loss record relies upon a team's offense, bullpen, and defense. ERA at least removes offense from the equation, and WHIP takes out the bullpen. None of these stats attempt to remove defense though. When evaluating pitchers, we should be interested in their ability independent of defense. I'd like to use a variety of defense-independent pitching stats to evaluate the 2009 Pirates.
There are a variety of stats that attempt to remove defense from the equation in measuring a pitcher's performance. Nate Silver of Baseball Prospectus fame derived QERA which uses a pitcher's strikeout rate, walk rate, and GB/FB ratio. Tom Tango's FIP switches out GB/FB ratio in favor of home run rate. The Hardball Times took FIP a step further with xFIP when they attempted to normalize home run rates, as it is believed that pitcher's have little control over their home runs once you account for their fly-ball rates. Lastly tRA is similar to FIP but looks at the character of batted-balls (groundballs, fly-balls, and line drives). Generically all 4 of these stats can be referred to as defense-independent pitching stats (DIPS).
You could make a decent argument for using any of these stats, but I won't do that here. Instead I'll take the average of all 4 in my analysis. If we are to use an average we should first make sure that all components are on the same scale, and it turns out that QERA, FIP, and xFIP are all on the same familiar scale as ERA. Since tRA is on the scale of runs allowed (RA), we can multiply by .92 to put it on the ERA scale. This wouldn't be much of a sabermetric post if I didn't come up with some sort of goofy acronym/name for this stat, so I'll call this average of several defense-independent pitching stats SuperDIPS. Thus SuperDIPS = (QERA + FIP + xFIP + (0.92*tRA)) / 4.
I'll begin with the pitcher who appeared to many to have the best season of any Pirate starter in 2009: Ross Ohlendorf. He led the starting rotation with an 11-10 record, 3.92 ERA, and 1.23 WHIP, so many would claim that he was the best according to the stats. However, SuperDIPS tells a radically different story. His FIP was 4.72, his xFIP was 4.74, his tRA was 5.14, his his QERA was 4.75. All 4 stats tell almost the exact same story, and in turn his SuperDIPS is 4.73. That is solidly below-average across the board. Now that is above replacement-level for an MLB starter, but it's nowhere near the level that he appeared to play at based upon more mainstream stats. I know a lot of Pirate fans are very optimistic about Ohlendorf and thought that he was one of the few bright spots on this team, but I believe he still has a long way to go if he is to be an above-average MLB starter. The results for the Pirates top 4 starters this year are in the following table:
It appears that Paul Maholm was actually the best Pirate starter in 2009. Many thought this season to be a disappointment for him, but he was solidly above-average. In fact, you can pretty much flip the results of Maholm and Ohlendorf for them to align with public opinion. Duke was very mediocre (nothing really new there), and Morton was very similar in much less playing time.
I'm not saying that SuperDIPS is better than any of those stats individually, but different variants of DIPS sometimes tell slightly different stories. Rather than analyzing the strengths and weaknesses of each one, I thought it would be interesting to just combine them all into one. The main thing to take away from the Pirates' perspective is that we can expect Maholm to be pretty decent next year while we actually need to look for a lot of improvement from Ohlendorf for him to be the #2-#3 type starter that a lot thought he was in 2009.
(This post originally appeared on my sabermetric website).