Rodrigo Lopez: Better Than You Think

In honor or Rob Neyer announcing himself as one of us, I’m going to pull out one of his favorite toys, the Player A/B comparison. The numbers are from 2010.

Player A: 215 IP, 2.46 BB/9, 5.05 K/9, 43.4% GB%, 4.60 xFIP, 88.0 MPH FBv
Player B: 200 IP, 2.52 BB/9, 5.22 K/9, 37.6% GB%, 4.70 xFIP, 88.2 MPH FBv

Pretty similar, yeah? Let’s go with career numbers, for more context.


Player A: 1,675 IP, 2.73 BB/9, 6.01 K/9, 40.2% GB%, 4.49 xFIP, 88.5 MPH FBv
Player B: 1,246 IP, 2.76 BB/9, 5.84 K/9, 41.9% GB%, 4.42 xFIP, 89.3 MPH FBv

I’m going to go with Still Very Similar for $200, Alex. They certainly weren’t treated as equals this winter, though.

Player A is Bronson Arroyo, who signed a three year, $35 million contract despite already being under team control for 2011. Player B is Rodrigo Lopez, who signed a non-guaranteed, minor league contract with an invite to spring training yesterday.

Now, let’s be clear – there are differences between Arroyo and Lopez. Arroyo has thrown 200 Major League innings in six consecutive years, while Lopez’s 2010 was his first year getting full time work in the big leagues since 2006. He had Tommy John surgery in 2007 and has spent a couple of years working his way back to the big leagues after rehab.

Arroyo also has performed slightly better than Lopez in two categories not listed above – HR/FB rate and BABIP. For his career, Arroyo’s allowed home runs on 9.8% of his fly balls and has a .282 batting average on balls in play. Lopez, meanwhile, has given up home runs on 11.9% of his fly balls, and his batting average on balls in play is .299. These differences drive their career ERA gap, but even that isn’t as large as their respective reputations might have you believe.

Lopez’s career ERA is 4.85, just a bit worse than his xFIP due to the inflated home run rate. Arroyo’s career ERA is 4.19, a bit better than his xFIP due to the deflated hit rate on balls in play. However, even these numbers don’t suggest a drastic gap between the two. Extrapolated to 200 innings, the ERA gap is equal to about 15 runs per year, and that’s if you don’t add in any regression for HR/FB or BABIP from their career averages.

Given their similar BB/9, K/9, and GB%, the actual gap in talent is probably a bit smaller than ERA would suggest. I’d guess it’s probably more like 10 runs per year, which gives Arroyo some credit for his history of holding his BABIP down, but also reflects the variation in that kind of skill.

10 runs per year is equal to about one win. Even if you want to give him the credit for the full 15 runs, that’s only a slightly higher win value. If you want to be aggressive with playing time projections in order to factor in Arroyo’s durability, maybe you can push that all the way to two wins, but it’s basically impossible to argue for any gap beyond that.

A one-to-two win gap between similar-ish pitchers just does not justify an extra $11 million per season with an additional two year commitment. The Braves essentially got Bronson Arroyo Lite for free, while Bronson Arroyo Home Premium cost as much as Paul Konerko. That just doesn’t make sense.

A lot of teams could have used a guy like Rodrigo Lopez at the back-end of their rotation, especially at an asking price not that far over the league minimum. It’s not like Lopez landed in a great situation with the Braves, as their pitching depth makes it questionable whether he can even make their rotation. Given all the money being thrown around this winter, there should have been some cash – and a major league rotation spot – available for Lopez.

Dave is the Managing Editor of FanGraphs.

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Rodrigo Lopez appears to be a walking insurance policy.