Would that change if it wasn't a dunk but a one handed runner or tear-drop or floater (whatever) from a smaller gaurd ? Because in that scenarios there is a chance the shot is a miss and Perkins is now a threat on the rebound while the corner 3 threat is momentarily nullified.
Perkins slid under before that would have been Foye's decision to make. Foye isn't boxing out Perkins that far under anyway.