Even the "best" umps are going to miss pitches. The zone is called far, far more accurately than it was in 30-40-50 years ago.
Yes, and bad umpires miss a
lot of pitches. If you believe guys like Bucknor and Angel are fine (he's gone at least), that's an opinion. I think a higher standard for umps is called for and if this system calls attention to the major outliers, great.