The pundit, speaking to Football Insider, believes Colback could be a star in the second tier – but cash is a potential stumbling block.
“He’s a decent player. Is he good enough to step into a Premier League side and play week in, week out? Possibly not, but he could do a fabulous job in the Championship but I’m guessing his wages are quite high. That’s probably put off a lot of clubs,” said Mills.
“As we know, Newcastle are unlikely to fund part of that deal and help anybody out. A quality player that will have to bide his time. You expect him to be a Steve Bruce kind of player; hard working, just get on with it.”
Colback could leave United with transfer windows across much of Europe remaining open until tonight.