I think Bogut has picked up defensively this year. Whilst his charges are down his blocks are up. He has been criticized for his lackluster blocking in the past. This year he is attacking the inside shot as a 7 footer should and becoming dominate (at times) on the defensive end, well as dominate as any Buck and that's not saying a whole lot.
On the offensive side his assists are down a bit. He's averaging the same as last year in points and rebounds, but shooting a worse %. He really needs to improve his free throw % (56% is Shaq-like). His minutes are down a tad this year due to foul issues, but this could also equate to his improved shotblocking and going after the shooter.
The times I've seen him this year, Bogut and Mo Williams seem to have a very good understanding and work well together.
My biggest gripe with Bogut is his that he is inconstant. Look at his last 5 games as an example:
Minny: 8 points / 13 rebounds
Boston: 4 points / 3 rebounds
Orlando: 11 points / 9 rebounds
Sac: 14 points / 9 rebounds
Portland: 21 points / 5 rebounds
You are never quite sure which Bogut will turn up. The bad one (4 points / 3 rebounds) or the very good one (23 points / 12 rebounds / 4 blocks or 11 points / 17 rebounds / 5 blocks).