Why are the Saints so bad at running the football?

Our Oline has regressed every yr since 2020. We had the #5 Oline according to PFF in 19 . Still had a top 8 one in 20. In 21 we dropped to 18 and last yr we fell off the cliff to 21. Why the decline? 1st in 21 Dan Roshar was moved from Oline coach to run game / TE coach. That started it, then in 22 we lost Armstead to Miami. Now TA was usually hurt a good part of the yrs he played but when he played he was one of the best. Last yr we made the big mistake of hiring Doug Marrone a guy that didn't last 1 yr under Saban before he got fired.. Only real change in personnel is Armstead , yes he was our best O lineman but 1 guy does not an Oline make. When players regress badly you have to look at coaching.
Now the guy that had us a top 10 ranked Oline all the time he was here is not even with the team now , Dan Roshar. He's coaching the Oline @ Tulane. Another ball dropped by DA