Tom Tango notes that the various pitch framing measures yield very similar results as Savant, Steamer, and Shadow Zone strike rate are all about 90% correlated. What I found more interesting is the year-to-year correlations:
Is one better than the other? To the extent that I would choose a winner, I would choose Steamer. If we look at year to year correlations of Savant to itself, we get r=0.51. We also get the same correlation if we run a correlation of Steamer to next year’s Savant. And we also get the same r=0.51 correlation with Savant to next year’s Steamer. Where we get a slight win is Steamer to itself has an r=0.56.
TangoTiger.com
If I am reading this correctly, asking if a catcher is going to be as good or bad at pitch framing next year, you can flip a coin and get as good an answer. That tells me pitch framing might not be the consistent skill that we are led to believe. There is probably a lot more going on than the ability to pull pitches into the strike zone.
I also hope that one factor is that umpires see the results at the end of the season and adjust their strike calling accordingly. The umpires may be doing Bayesian updating. They have priors for a ball being caught in a certain location being a strike, and based on new information about a particular catcher, they move that prior up or down. We know MLB reviews ball and strike calls to help umpires improve, so maybe the r=.5 isn’t that surprising.
Nice to see the cheating catchers are being caught.
“If I am reading this correctly, asking if a catcher is going to be as good or bad at pitch framing next year, you can flip a coin and get as good an answer.”
I don’t think this is correct. It’s saying that about half of next year’s performance can be predicted based on this year’s performance, and thus there is a relationship between year 1 and year 2 (ie, framing is a repeatable and identifiable skill). If there were no relationship, you’d flip a coin and be right as often.