Instead of the magical "bad calls even out in the end" rule, I think it's worth considering that, when every team gets 27 outs instead of the game being played on a clock, and when there are 162 games (approx 4374 outs) in a season, the impact of any one play in terms of an entire season is severely insignificant. Add to this insignificance that questionable calls go in all directions over the course of the season, and replay turns out to be pretty inconsequential. Even considering that, however, using instant replay during the season is worthwhile because it keeps the process in practice for when playoffs roll around, and during the playoffs, anything outside of balls/strikes should be fair game.