The NL Central Rotations

In this afternoon’s impromptu chat session, I was asked which team I thought had the best rotation in the National League Central. This question was clearly inspired by the Brewers recent acquisitions of Zack Greinke and Shaun Marcum, giving them three formidable starters to match up with the group down in St. Louis. However, I didn’t choose either of those rotations as my pick for the best in that division. Instead, I went with the Reds, with the caveat that Aroldis Chapman ends up starting for them. Am I nuts?

We’re somewhat lucky in that Dan Szymborski has already unveiled his 2011 ZIPS projections for these three clubs, so we can use his system to stack up their starters side by side. Let’s start off with the Reds, while keeping in mind that ZIPS is not projecting playing time for a given roster – it is just estimating what a player would do if he was given the allotted amount of innings in the big leagues next year. For reference, league average according to ZIPS is a 4.35 ERA.

Travis Wood: 178 IP, 161 H, 17 HR, 62 BB, 147 K, 3.64 ERA
Edinson Volquez: 108 IP, 90 H, 11 HR, 55 BB, 115 K, 3.66 ERA
Johnny Cueto: 191 IP, 183 H, 23 HR, 62 BB, 156 K, 4.01 ERA
Bronson Arroyo: 201 IP, 195 H, 27 HR, 60 BB, 127 K, 4.21 ERA
Mike Leake: 168 IP, 174 H, 20 HR, 54 BB, 109 K, 4.34 ERA
Homer Bailey: 155 IP, 155 H, 18 HR, 63 BB, 124 K, 4.47 ERA
Matt Maloney: 161 IP, 169 H, 22 HR, 43 BB, 116 K, 4.47 ERA

That’s seven legitimate major league starting pitchers, and we didn’t even mention Chapman, though ZIPS isn’t overly high on him for next year. The straight weighted average ERA of those seven pitchers is 4.13, which is decent enough, but weighting it that way overestimates the quantity of innings that will be pitched by the reserves. If we re-weight the innings so that the first four starters each get 180 IP, and the last three combine for another 180, then their overall ERA comes in at 3.99.

If we do the same thing for the Cardinals (the exact numbers for each starter can be found by clicking the previous link), we get a straight weighted average of 3.86, and a re-weighted average of 3.67. The Brewers come out at 3.93 with a straight weighted average, and 3.74 with a re-weighting of innings. Both of those numbers are significantly better than what Cincinnati came out at, so maybe I am a little nuts, as ZIPS sees the Brewers and Cardinals as similar in terms of quality, but both a good bet ahead of the Reds.

However, giving each team’s top four starters 180 innings apiece, and then splitting the final 180 innings among the teams #5-#7 starters (which was done on a 75-75-30 basis) , assumes that each team will have something approaching equal health for their starters. All three teams have guys with a history of arm problems, and projecting pitcher injuries is never easy, but Jeff Zimmerman has recently done some interesting work on the likelihood of various pitchers landing on the DL. One of the first things you might notice in the spreadsheet is that Chris Carpenter, Jake Westbrook, and Shaun Marcum are three of the 10 pitchers that are given better odds of landing on the DL than staying off of it all season.

Does this mean that the Cardinals and Brewers will definitely get fewer innings from their top end guys? No. We’re not at the place where we can project specific pitcher injuries with any kind of reliability. However, both Milwaukee and St. Louis are more vulnerable to injuries to their frontline starters, as they lack the back-end depth that the Reds have accumulated. If Carpenter or Marcum do miss significant time, the drop-off experienced will be significant, and could serve to put either (or both) teams behind the Reds in terms of starting pitcher performance.

I think we can draw two conclusions out of all this – I probably overstated the strength of the Reds rotation a bit, as the Cardinals and Brewers strength up front does outweigh the Reds depth if everyone stays relatively healthy (and Chapman doesn’t become an impact starter next year). However, both St. Louis and Milwaukee have opened themselves up to significantly more risk than the Reds, and the gap is small enough that one extended trip to the DL by one of their aces could tilt the balance of power in Cincinnati’s favor.

It really comes down to a risk versus reward argument. The Reds probably have the lowest of both, so in a situation where injuries abound, they will likely come out on top. If everyone stays healthy, they’ll end up trailing their two competitors for the division’s best rotation. It really will come down to just how many arms end up hurting next summer.