I will have to disagree and say that it would be an arbitrary terrible rule that would unnecessarily complicate and prolong the game and make no impact on anything. What is the penalty, a do-over? Lefties most certainly do not face a disadvantage, they are closer to first base and have the platoon advantage 70% of the time. Plus the great sluggers can overcome the shift anyways, last time I checked Ortiz was still putting up big numbers with 2 second basement and 2 right fielders every AB. As other have pointed out the arbitrary-ness of an infield shift rule is asinine. Why can outfielders shift? Why can pitchers try to pitch on the corners? Why can you pitchout? Why can you hold runners, why can you bring in an extra IF with the winnings run on third...basically, why would this be the only defensive strategy that is somehow outlawed? Good points. My initial reaction was this is terrible. Then I thought, maybe it could have a simple rule, like two IFs per side of 2nd, but you are right, how do you enforce that? I think you are swaying me back to my original take, let the batters figure it out and they will stop doing it.