I'm not a fan of going to completely automated balls and strikes, but I do think that it is headed there sooner than later (at the MLB level). As for this idea, if I recall correctly, it is similar to what they did in the minors at some levels last season as an experiment. The first thing they needed to fix when all this started was the auto-strike zones had to be adjusted for each individual hitter, they finally figured that out and fixed it. Giving each team 3 immediate challenges, which can only be used by the hitter, pitcher, or catcher, seems to be they best way. If you win your chlannege, you keep it unless/until all 3 are used up. But the challenge must be immediate... not checking with your manager and all that stuff. Then the call turnround from upstairs needs to be in 10-15 second range, not 30-45.