There's not much moderation in this thread, is there? Everybody seems to be either "Bill Walker is going to make post-GPA life good" or "I expected a lot from him this year, he didn't deliver, and he won't next year either."
First of all, the kid is 21. If he came in and contributed right away, he would have shocked everybody not wearing Green glasses. Hollinger may not be everybody's favorite person on this board, but I thought his preseason analysis was dead on: "The hope is that he'll regain his pre-injury faculties over time, but anything they get from him this year is gravy." Since he came onto this team and immediately became our most athletic player whose name isn't Rondo (and possibly even including Rondo) and showed flashes of real skill in the meantime, I think his future looks pretty good. In the meantime, he gave us some minutes backing up Pierce and playing emergency PF where he didn't hurt us on the court. Given that Hollinger's prediction was about the most optimistic that I read this year (most thought he'd either spend the year hurt or in the D League), I'd say we got a lot of gravy from him this year.
As for next year, I think moderate progress from this year is fair enough to expect. If he can show up next year with less fouls, better defensive rotations and an improved handle, he'll have set himself up very well for a spot in the rotation. I think that's pretty reasonable - if he can't do that, then I definitely can't see him making life after GPA any easier (which is a long shot for a 47th pick anyway, keep in mind).