Well, why not?

For the first time Tuesday, baseball general managers recommended instant replay be used to help umpires make difficult decisions.

The recommendation, by a 25-5 vote, was limited to boundary calls — whether potential home runs are fair or foul, whether balls go over fences or hit the top and bounce back, and whether fans interfere with possible homers.

I think that’s a reasonable use of instant replays.  I don’t think it should be used for balls/strikes.  That would make the game even slower.