80s players seem to have high/good error ratings. This issue seems to start (or end? POV is hard
) in the 70s.
I personally think that the error ratings are designed to approximate the fielding percentages the players had in the year their card represents. In another thread, someone brought up the fact that these percentages used to be lower due to a number of factors, including field quality, glove quality, and trends in official scoring (ie much more lenient with errors now). I don't know if all this is true, but it makes sense in my head.