Good article on ESPN (I know, oxymoron, right?) in which researchers went through 184 game broadcasts this year and tagged the close calls in the games, and whether the umpire got it right.
They tagged 230 close calls, and
Of the close plays, 13.9 percent remained too close to call, with 65.7 percent confirmed as correct and 20.4 percent confirmed as incorrect.
They did a survey of 40 HOFers and of them 70% said that an "acceptable" amount of errors was 20% or below. The other 30% declined to answer....
What is an acceptable amount of error to you?