And the dev chat ruling on the catcher's input...
How much and what sort of impact does a catcher's pitch-call rating have on a pitcher's performance? (will_prosper - Hall of Famer - 11:48 AM)
A catcher's pich calling rating impacts the pitcher on the mound's OAV used in the engine. The difference between an average catcher and the worst or best catcher is significant. We don't want to provide exact numbers. The best way to see this setting at work is to compare your #1 C with your #2 C since they both are receiving for the same pitching staff.
Which I believe to be true to the extent of ~.5 ERA difference between a 50 PC and an 80 PC, on average.