Buff is held to a higher standard than most and rightly so for being a veteran D-man wearing A with a big contract. Also the thing with Buff is a lot of the time you have this feeling he could be great BUT... the mistakes he makes are often the kind that make it easy to question his dedication to defense and overall team play - but I'm willing to cut him some slack in this respect, I think like many people have said part of it is just trying too hard and trying to be THE GUY, while at this stage it would be enough if he just played solid.
As for the comment on ice time, I haven't seen the interview (or read it if it wasn't video) so can't comment on what exactly was asked and answered. But if you're used to playing more like 25-30 min, playing 18 must feel like a different game and having trouble to focus and stay in the flow of the game is understandable. Especially if you're like Buff, for someone who plays a smart "low-event" style D-game I guess it might be easier, but Buff seems to go more by instict and gut-feeling or whatever, which also could explain why both his lows and highs are so peaky.