Tough question. On one hand we saw what he did last year, and we know he has what it takes to beat even Rossi. He won the title by a long way last year and picked up a lot of that lead in the last 3rd of the championship. A few wins would bring him right in the mix, and if the others have any problems (similar perhaps to what he's had) then it wont seem like such a big deal.
On the other hand, we've been here before with riders who win world champiosnhips and for a variety of reasons are unable to repeat the feat in the following year. The optimistic amongst us will maintain that he could return to old form at any given time and that it's not over till its over, however i said that so many times in 2006 i struggle to believe it myself now.
Can Casey do it? Yes
Will Casey do it? ................................................................