I heard a report on 106.7 yesterday (or Thursday), I think it was on Lavar's show - where someone did the analysis and said that all things considered, there have only been two other teenagers in the same league offensively as Harper has been this year - Tony C. and Griffey Jr.
I don't think it's righty/lefty as much as growing pains. He didn't hit lefties all that great in the minors but I don't have the same quality of stats. I would believe he probably had more troubles than he has now. That's natural for a young player, that's what development is all about. But as to how long,IDK I think he's pressing more than any real flaw. Give him some time off let Tyler get some AB's see if that helps.