I'm glad you cleared that up. I spent a long time wondering what he meant.
There was an important game with Chelsea, the one in which Torres scored an idiocy of a goal right at the death. Many blamed Nastasic for that, and it sort of cemented the idea that he was a mistake-maker, but I reckon Hart was probably 70% to blame, and Nastasic 30%.
I was incredibly annoyed at the end of that match. In fact, it prompted me to sign up on here and post my first post (in which I said quite a lot of stupid things, if I remember rightly, establishing my credentials in the process).