I'll comment on the pass blocking too.
I think it is a combination of two things. First, we don't have a BB who is a constant threat on the dive and inside veer. That means that nobody much pays attention to holding ground and stopping us up the middle first. If we had the combo we had last year nobody would be teeing off on a pass rush; they'd be worrying about what'll happen if they tried it. Second, the overall speed of the O is down as well. That means the LBs and DBs aren't holding ground to stop us reaching the edge. They are coming up fast. Result: on passing downs - and those are more identifiable now - they press and blitz.
In short, I don't think the OL has regressed; we didn't look all that hot at the first last year. Then we began to hit the dive and speed up our execution. All of a sudden, from UNC on, the 2014 OL was the greatest thing since sliced bread. If our execution continues to improve, I'm betting that the pass blocking will too. But that's a hypothesis and we'll have to see.