The Italy international is due to leave the Premier League champions before tomorrow's transfer deadline after reportedly agreeing a deal with AC Milan.
"I'll only remember him as a great penalty-taker," The Express quotes Royle as saying. "Apart from that, I have never understood what all the fuss is about. He has got no work-rate.
"I have never seen a player walk as much as he does on the pitch. He doesn't score enough goals and there are too many headlines off the pitch, what with the parking fines, fireworks and silly T-shirts. If you look back at City's run-in last season, when they won the Premier League, he was a nightmare."
Reports have claimed that the 22-year-old has taken a significant paycut to return to Italy.