[qam1]

Also, each ump has their own strike zone. Players don’t generally get mad as long as they are consistent.

So for example for a player it is preferable for an ump can consistently call a low strike which would lower his percentage number vs a ump with a better number but moves his strike zone around.

[Scoutmaster]

Each umpire does have his own strike zone. That's been the case as long as I can remember and I assume it was true when Hoss Radbourn was pitching.

Just for reference, Baseball Savant maintains a database of all MLB pitches thrown. You can search by type of pitch, count, player, runners on base, home or road games, outs, and various other persnickety factors or combinations thereof.