I think Rafa has already seen through him.
Last season you could allow for Rafa going for 'experience' (even if it was clapped out shite like Cisse, Tiote, S.Taylor etc) and Colback came under that bracket. A supposedly solid performer who you allegedly know what you're getting from.
The performances of Hayden from day one, and since Shelvey has woken up, have definitely moved him into third choice. He'll still get starts and minutes off the bench, but I honestly believe Rafa will phase him out over the next 12-18 months. He has defined roles for his central pair and I don't think he fits into those so well.
And he's shit obviously...