So here's my trying to objective view (best stated when not watching a game and getting p----d off). Danny built the team figuring Hayward was at least picking up his option. 4 all star level starters + Theis and Smart. Fill in the blanks on the rest with cheap guys you draft.
Turns out he's drafted pretty poorly aside from the Jay's and in particular the 2019 draft was terrible. Hayward unexpectedly leaves, all he can get is a trade exception, figured Teague was a solid cheap signing (he wasn't) and TT seemed like a good signing but to date has not moved the needle. What's left is a top heavy roster - but with depth that you can't win with. Its too young and/or just not talented enough.
Injuries have piled up, games are coming too fast, several players have tuned out their coach etc.
A lot of this is Ainge's fault, though he also hasn't had the best of luck. It's going to take time to fix and there is no quick fix move apparently available right now.
The one conclusion - and I'd like to emphasize this for all his haters everywhere - Hayward's departure wrecked this team.
What to do about it:
Short term he has to focus on keeping the Jay's happy (people don't focus enough on this), and try to find a big or two who can defend without fouling. Theis and G Williams have both regressed in that department. And R. Williams despite his hustle and athleticism is not a great defender.
Unfortunately it's going to take some time and won't be solved this season. They probably need to start focusing more on the long term and worry about re-building a winning culture here. Guys who won't be part of that - either due to ability or attitude should be moved as quickly as possible. Your keepers are the Jay's and probably Smart because of his impact on the culture. Everyone else with value is available for the right price.
He also needs to decide if his coach is up to the job still. If the Jays won't play hard for him, he needs to go. Brad's a good coach but there is a shelf life with most NBA coaches.