The former Everton midfielder feared his injury record would work against him.
Asked if he was surprised at the transfer, he said: "I was a little bit, yes, because of the injuries - it was a good surprise though.
"I'd seen the German doctor Muller-Wohlfahrt a couple of months before City came in so I felt I was fit at the time but I obviously wasn't. I probably didn't do enough work after getting treated by him which I know now.
"I don't really think about the price tag or anything like that. When you're on the pitch you can't think about what the fans are thinking. It's natural when you've spent that much money and you've won the league last year, you do expect a little bit of something in return.
"I feel as though the fans saw a little bit more of me (against Chelsea) but there's still a lot more to come in my opinion."