While there can always be some subjectivity in scoring including on passed balls and wild pitches, I really don't this as difficult of an area to score as are some others. And as was stated in another recent thread, coaches and parents can choose to "blame" others for mistakes (e.g., the catcher should block balls in the dirt), but the scoring rules are the scoring rules, and I think it's important they be done as consistently as possible.
In the case of WP and PB, the scoring rules state that balls that hit the ground before they get to the catcher are WP's if a runner advances who wasn't stealing already (scorekeepers may sometimes need to ask coaches about that). If a ball goes over a catcher's head, or is wide of the glove and they never touch it, that should be scored a WP as well. If a ball goes into the catcher's glove and then pops out and the runner advances, then that's a PB. The only thing that's really subjective are those that hit the glove in the air but which the catcher is unable to hang on to ... that's where the reasonable effort subjectivity comes into play on the part of the scorekeeper. The majority of these are probably PB's, but there's just no set rule. And you can't somehow assign it based on how far off the plate it is ... it depends on the speed and direction of the pitch, the reach of the catcher, etc.
Just two other points ... passed balls are not considered "errors" and don't affect the catcher's fielding percentage, but they are scored similarly to errors for the purpose of calculating earned runs ... i.e., you reconstruct the inning as if the passed ball did not occur. And no, the batter doesn't get an RBI if a runner scores on a PB or WP.
