It's impossible to predict the end of this draft. Bill Walker is rumored to have a promise from Detroit at 29, and I find that rumor to be credible. He's the kind of kid that Joe Dumars likes. I expect Douglas-Roberts to be gone as well.
When Ainge says he thinks he can get a player to help right away in this year's draft he's probably blowing smoke in a attempt to trade the rights to the player selected (he can't trade the pick itself, since he traded the Celtics' first rounder last year).
If he wants someone NBA ready, maybe he'll stretch for a player like Mike Taylor, who could at least give Rondo some good workouts in practice. Otherwise, assuming Walker and CDR are goine, everyone else who might conceivably be there at #30 (unless there are major screw-ups by other GMs) is either a project or is not an NBA caliber talent.
I'm strongly coming around to the view that they should go for a project 7 footer (prefereably an International player) and hand him over to Brian Doo and Clifford Ray for a year of physical conditioning, strength training and NBA boot camp. That's what they did with Perkins in his first year.