I agree with Jaycelt; it doesn't make sense to assume Chalmers wouldn't get PT here. I'm pretty sure he would; at least he'd get Pruitt's minutes, although I believe he'd earn some more (not considering that had we drafted him, we'd have gone differently in the FA market).
Chalmers reminds me of Gerald Henderson: he won't create or fix plays, but he'll initiate the offence, hit some shots and play good defence. I think he's going to be a very good backup guard for good teams through out his career, but he surely can handle the starting spot, especially if paired with a playmaking wing. More importantly, Chalmers is pretty much a finished product; he'll improve his shot-selection but not a lot more. He's already a very solid rotational player, I don't understand how people assume he wouldn't play in some NBA teams.
Chalmers was one of my favourite players for the C's in the draft, so I guess I'd still rather have him; but it's hard to say having seen so little of Giddens.