Murray played with Zaha at Crystal Palace.
He told talkSPORT: “It's a tough one.
“Palace definitely bring the best out of him and I'm sure it would be a worry in Wilfried's mind that if he was to move again it may not go as well.
“I'm sure he'll be a little bit scarred from the Man United move.
“But for me, I've seen him come through as youngster and he is a fantastic player, the only way is up for him.
“And I honestly believe that if Fergie was still at Old Trafford when Wilfried went up there, he would be one of the best now."