Cheng isn't getting in the way of Arias. Once they are comfortable with Arias's progress, he's going to WOO and getting 100% of the SS reps. Probably by the end of June. Mookie was promoted to PAW on June 3 (OPSing 994). If he's still absolutely raking like a monster, he'll get a very early promotion. Mookie was up and down from there, but was still OPSing around 900 in AAA (the number where you are really knocking the door down for a promotion to MLB IMO).
Yeah, that 900 OPS is really the sweet spot for an MLB prospect promotion to me. Anthony got there. Mayer didn't.