How good is the Nats’ rotation, really?

Early in the season, small samples are the bane of statistical analysis. But now that we’re nearly 50 games and one-third of the way through the season, we’re starting to get samples that are large enough to really be indicative of performance. Let’s take a look at the Nats’ starting rotation (all of whom have now pitched at least nine starts and 50 innings).

As Steven at FJB has noted, run scoring is down and the old performance standards may be deceptive.  I like to look at things by seeing where players fit within a distribution, so I went to fangraphs and looked at all starting pitchers with at least 30 innings pitched through May 25 (a total of 143 pitchers). I sorted them into quintiles; for each quintile I’ll list all of the NL East pitchers, with the Nationals in bold. (Note that within each quintile, I’ve sorted them by team, not by level of performance.)

I think quintiles are interesting because people often talk about pitchers in terms of numbers one through five (“he’s a potential ace” or “he’s just a number four or five pitcher”). Looking at quintiles, an average team would be expected to have about one pitcher from each quintile. Good teams, obviously, tend to have pitchers concentrated in the top quintiles, while poor pitching teams will have them in the lower quintiles. We’ll see that in what follows.

First, here are the quintiles for ERA– (that is, ERA that has been adjusted for park effects and normalized so that 100 is “average”).

First quintile (ERA– of 42 to 78): Jair Jurrjens, Tommy Hanson (ATL), Josh Johnson (FLA), Roy Halladay, Roy Oswalt (PHI)

Second quintile (79 to 92): Ricky Nolasco, Anibal Sanchez (FLA), Dillon Gee (NYM), Cole Hamels, Cliff Lee (PHI)

Third quintile (93 to 107): Brandon Beachy, Tim Hudson, Derek Lowe (ATL), Livan Hernandez, Jordan Zimmermann (WAS)

Fourth quintile (109 to 129): Jonathon Niese (NYM), Tom Gorzelanny, Jason Marquis (WAS)

Fifth quintile (131 to 201): Javier Vazquez, Chris Volstad (FLA), Chris Capuano, RA Dickey, Mike Pelfrey (NYM), Joe Blanton (PHI), John Lannan (WAS)

I notice that four of the Phillies’ five pitchers are in the top two quintiles, while none of the Nats’ pitchers make it higher than the third quintile. All five of the Braves’ pitchers are in the top three quintiles,  while only one Mets is above the fourth quintile.

There’s still a lot of noise in ERA statistics. A measure that tends to be more stable in small samples is xFIP, which is an ERA-like measure that is based just on strikeouts, walks, and fly balls (to pick up a pitcher’s home run tendency). Although these seem like a small number of indicators, they correlate very well with pitching ability. The following distribution looks, to me at least, like a more accurate distribution of pitching talent:

First quartile (xFIP of 2.26 to 3.22): Brandon Beachy, Tommy Hanson, Derek Lowe (ATL), Josh Johnson, Ricky Nolasco, Anibal Sanchez (FLA), Roy Halladay, Cole Hamels, Cliff Lee (PHI)

Second quintile (3.24 to 3.58): Jair Jurrjens (ATL), Chris Volstad (FLA), Joe Blanton (PHI)

Third quintile (3.59 to 3.94): Jonathon Niese (NYM), Roy Oswalt (PHI), Jason Marquis, Jordan Zimmermann (WAS)

Fourth quintile (3.94 to 4.32): Tim Hudson (ATL), Chris Capuano, RA Dickey (NYM), Tom Gorzelanny, Livan Hernandez, John Lannan (WAS)

Fifth quintile (4.33 to 5.57): Javier Vazquez (FLA), Dillon Gee, Mike Pelfrey (NYM)

This distribution really emphasizes how good the pitching is that the Nationals face in the NL East—nine of the top 29 starting pitchers in baseball as measured by xFIP pitch for Atlanta, Florida, or Philadelphia. (Maybe this helps explain why our batters our struggling!)

So, what do I take away from this analysis? I find it pretty sobering. The notion that all the Nationals need to do to have a competitive pitching staff is to wait for Stephen Strasburg to return and watch Zimmermann develop into a number two starter is naive and wrong-headed.  That might be good enough to produce an average rotation in another division, but in the NL East, it simply wouldn’t be enough to be competitive. Along with Strasburg and Zimmermann, we’ll need at least two more first or second quintile starters if we hope to compete with the Phillies, Braves, and Marlins. One of Marquis, Hernandez, or Gorzelanny might be adequate as a number five. As I discussed in an earlier post, Lannan probably won’t or shouldn’t be around much longer.

Mike Rizzo has his work cut out to develop, trade for, or sign two more high quality starters. But he can’t expect to win if he continues to field a team with average-to-below-average starters.