This team is all set up for a new HC with a capable staff to come in and start winning after adding a few players on offense. All he'll need to do is to get Grier to add some competent veterans on the o-line (sometimes miracles do happen!), add one or two WRs (who aren't always injured), and get one decent RB#1. They'll have money under the cap to sign some Free Agents and the draft to get this done. Refusing to get experienced veterans for the o-line and a strong RB#1 is why they failed to make the playoffs in 2021. Just those two fixes alone would have given them a better offense that could sustain drives, give Tua time to throw downfield, and score more points.
IMO, it wouldn't take much for a new guy who knows what he's doing to turn the Fins into a playoff team. I think that the biggest question would be Tua. Given a good line and running game, will he prove to be a consistent winner, or just an average Game Manager? Either way, fix the o-line, add another WR and RB and they can still be a playoff team.