Robson told the Manchester Evening News: “The problem for a player like Michael Carrick joining a new club is that he isn’t a dynamic player.
“He is a very intelligent player and is a wonderful passer of the ball but he doesn’t have that dynamism that hits you straight between the eyes and makes you an instant hit.
“United fans loved Roy Keane and they took to him right from the moment he arrived at Old Trafford as his game was in your face.
“It was obvious heart on the sleeve stuff and the fans love that. They love a tackler and an aggressive player. It is probably easier for those kinds of guys to make an immediate impression.
“Someone like Steven Gerrard at Liverpool is similar.
“You can take to him straight away because of his aggressive all-action style. Players like Carrick probably have to work that bit harder to catch the eye and it will take longer.
“But you can be sure that he will get there. I think United fans are already starting to appreciate what he can do. They’ve had to be patient. He will grow on them.”
Robson added: “Obviously, the United support would have wanted to see a like-for-like replacement for Roy because he was such an influential and inspirational player to lose.
“Sir Alex Ferguson would have wanted the same, believe me. It is certain he would have had his staff scouring the world for another Roy Keane or a Steven Gerrard.
“But they don’t grow on trees and that kind of player just wasn’t avail- able. It was always going to be virtually impossible to get the complete package and Michael Carrick isn’t the complete package as a replacement for Roy.
“I think the fans understand that and they will judge Michael on his assets which include his great vision and intelligent passing and eventually they will look back on his first season and see the difference he made.”