I think from a scheme standpoint, I have to imagine Buchner's skill set is much more advantageous for the 2022 ND team. Even if we accept the fact that his throwing may be below Pyne's ( FTR, I believe that it's undecided at this point), the ability and threat of him running will allow for more tactical scheming to make up for any potential shortfall.
Look at it compared to Coan last year. He was a statue and teams knew it. Now, the OL play clearly didn't help. But the offense was so up and down because it required high levels of execution given the skill sets of the QB and the rest of the offense. As we look to next year, there are probably 3 likely themes that will emerge....1) OL play will be significantly improved and will likely be the most consistent part of the offense 2) WR depth will be limited 3) there will be diverse skill sets in the backfield.
Looking at those 3 things and given what we know about TB and Pyne, I struggle to see where the offense is consistently put in better situations with Pyne. It's not a knock on the kid either BTW. I think it would be different if we were 7 deep at WR. But we don't have a roster for that as it stands today. The best way is to have a Power Spread attack that holds an extra guy in the box to allow for Davis, Styles, Mayer and RB's out of the backfield to be schemed open in the passing attack. It should be simple reads that makes the defenders have to read and react, giving our guys one step advantage. We don't need TB to be Brady Quiin. We need TB to be able to know pre-snap which 2 or 3 defenders to key on and make it easy for him. His legs will ultimately make his arm better.