Well, MRI should have been done with contrast if they wanted to look at the labrum.
I would suggest hitting up some of the stretches in the KStar mobility if that's the case if there's really no labrum or bony issues:
Most likely it's internal impingement of the hip much like the shoulder can gets internally impinged in a lot of throwing athletes.
I would suggest stretchin both ER and IR (here's IR -- http://ericcressey.com/wp-content/up...ch-300x225.jpg
); ER you can do with piriformis stretch or the KStar stuff.
And then also tennis/lacrosse balling the soft tissues in your quads, IT band, hamstring, glutes, especially glute medius/minimus and tensor fasciae latae