Dave Ziegler joining the Saints as an advisor for Free Agency and the draft (Saints permanently hire Ziegler as Personnel Advisor)

Perhaps, but the reality is you are going to lose a QB in Winston. Arguably you could sign a vet QB, and maybe the will, but DA's predecessor eventually worked his way out of new orleans because he didn't scratch off enough lottery tickets at the QB position in the twilight of Drew's career.

DA inherited that problem and despite Carr's nice finish to the year, if that wasn't enough to keep Pete, in theory it shouldn't be enough to solidify Carr as "the answer". If anything you should be looking to lean on Kubiak's insights into what they saw in Brock Purdy. Perhaps you aren't using a 1st on QB (or maybe you do) but to leave this draft without choosing one wouldn't be wise.
I don't think DC's and the offense's improvement was a reflection on PC as much as it was DC was healthy and the OL play improved from putrid to just average