I think the main thing is all the top end talent we lost between 2019 and this year. Either from free agency or retirement.
Filer and Matthews off the O-line being gone might be the answer to that question. Courtney Stephen and Adrian Tracy retired. Patrick Levels who was our big FA for the 2020 season before it was wiped out, is back in Montreal having never played for us (why were 2020 rosters / contracts not honoured for this year?)
Other big names that are gone though im not sure the details: Breaux, Cariel Brooks, Hajrullahu, Mike Jones, Leonard, Rico Murray, Rolle, Shortill, Tasker.
I think that list is mostly accurate. But you can see the losses on the O-line, secondary, kicker, recivers and various depth positions.
Not to mention the current starters injured: Wynn, Addison and Frey. Frey is a player I think we don't even realize how much we're missing, he was incredible in the half season he played before he was injured. Also wonder what our offense looks like once Burt plays and we team him with Kalenic.
But ya, sheer talent loss along with some out shape players likely from a year away is my analysis as to what's wrong.