I get your point about the passing going better with Pyne, and that could be all it is.
We don't know if the OL just clicked and started to play better, or if the poor play was because Buchner was making mistakes in calls that made the OL look bad. If it was the former, then we beat Cal with Buchner because his protection would be better and we would be able to run the ball. If it was the latter, we could still have beaten Cal if Buchner learned from his mistakes and made better calls, leading the line to play "better" against Cal as well, but we have no way of knowing if he would have. If we lost to Cal and were 0-3 with Buchner I do think we would have switched to Pyne for NC, and who knows how that would have gone at that point considering how he played against Cal in his first start.
I'm happy Pyne seems to have gotten over the obvious jitters he had versus Cal in the first half and settled down. Things look much better, especially against a weak NC defense. It is unfortunate that Buchner was injured and that it has cost him his season. It will be hard for him to get better without being able to practice and play. I have not lost all hope for him because he had two bad games with no protection and got injured. No one here should either.