Personal catchers are nothing new in baseball. Every catcher has different tendencies (as does every pitcher), so it's not surprising that certain catchers would mesh better with certain pitchers. Ryan Hammon at Rockies Zingers thinks Colorado has such a relationship between Tyler Matzek and Michael McKenry. Hammon takes a look at Matzkek's SIERA -- an ERA-estimator similar to FIP -- to show that the left-hander tended to do much better last season with McKenry behind the plate rather than Wilin Rosario.
To read more about Hammon's analysis, check out Rockies Zingers.