I'm at the office so I can't see the videos of the plays here, just the pictures.
It seemed to me from the pictures that Prince should have helped stop both Parker and Green's penetrations in plays 1 & 3 but he couldn't be bothered. He was the one that could have disrupted that play. In play 2 it seems like Pondexter at least tries to do that, but Parker was too fast for him and he then decides to stay with his man.
From this analysis it seems Memphis wing-defenders are just standing by as spectators. Was that the case in the actual game?