I think the important thing on the "getting off his blocks" criticism is that it's not like he was getting physically dominated. On the Addai play, for instance, it's not like he got blocked out of the way and turned around... It looked more like he was holding his ground while reading the play and just waited too long to actually go for the running back. That could be simply the speed of the game being greater than he realized, which happens to every rookie at pretty much every position.
The guy is coming from a system where he got to use his quickness to avoid blockers to one where he's now supposed to take them on and read the play, and it's a big change. Considering how bad he looked in preseason, I thought he did more than fine in his first real NFL action. I was worried like everyone that he might be a bust, but Sunday he showed enough to not worry about that anymore... IMO.