I hadn't seen Stokes be that passive since the first Xavier game. I'm not Stokes so I don't know what goes on in his head, but he definitely backed off physically once he got that technical.
You can look at it two ways:
Stokes got beat by a 7'1 white boy who will have a stint in the EURO league. Stokes is getting drafted for his rebounding and his control of the ball, not for his defense.
Stokes has averaged almost a double double all year and has looked great against NBA bigs. (Last year when UCONN came and he man handled Andre Drummond).
I didn't say stokes is terrible player, or anything. Just that he's going to have trouble guarding skilled PFs in the nba.