Catcher Defense Prior to 1953

With help from Sean Smith of baseballprojection.com (and of an unnamed team front office) and baserunning statistics from Pete Palmer, we now have incorporated catcher defense for the years 1890 through 1952 based on stolen bases, caught stealing, errors, passed balls, and, from 1925 on, wild pitches. Prior to this update, these players’ defensive abilities were judged only based on errors and passed balls.


My understanding is that WhatIf uses at least some historical data from Baseball-Reference.com. Does anyone know if BR.com is the source of historical defensive data? If so, it seems like a substantial adjustment to pre-1953 catchers defense on this site might be in order. Of course, whether resources would ever be dedicated to such an update is another matter entirely.