Yesterday, Baseball Prospectus unveiled new metrics for quantifying catcher defense. I highly recommend reading the introduction for yourself, but if you’ll allow me to crudely summarize, there are four key metrics presented:
- Swipe Rate Above Average (SRAA)
- Takeoff Rate Above Average (TRAA)
- Errant Pitches Above Average (EPAA)
- Called Strikes Above Average (CSAA)
The first two metrics measure a catcher’s impact on the running game through the rate at which they throw runners out (SRAA) and the rate at which runners attempt to run on them (TRAA).