It is not quite that many. According to Fangraphs, in 2015, there was an average of 288 pitches thrown per game. Of those, batters swung at 46.7%. That means umpires called an average of 154 balls/strikes per game. At an error rate of 14%, that is 21-22 missed calls per game.
I couldn't find any data on it, but I'm guessing that the majority of those missed calls were borderline.
Now that said, I understand if those numbers are still unacceptable to some. I understand why some people want as close to perfection as possible. IMO, the tradeoff of accuracy for non-automated strike zones is worth it. IMO, baseball, played and umpired by people, was not meant to be perfect.