By that logic we have no idea where Van Gaal will play any of our signings, even Falcao or Herrera because we aren't Van Gaal. Rojo is 100% a centre back, I'm not sure why you don't believe everyone else here. Just like blind is definitely a defensive midfielder. No maybe he's better here, no, he is a midfielder who can fill in at left back. You're saying maybe might be somewhere else, but it just isn't. Their best positions are centre back for rojo and defensive mid for Blind.
As for Shaw, he clearly rates him, just he wasn't fit in the first week. He's had a few press conferences since where he said how he's much improved in that regard and how he's now a role model in the dressing room. People took his one comment about not being fit enough yet too literally basically.