In Barry's defense, Barry's defense did miss 20 tackles... (Sorry, couldn't resist that pun).
If we keep MLF this year (likely), I'm ok with that based on previous seasons, but beyond changing D-coordinator, two major changes are needed:
The team needs to come to the game prepared. Whether it is development of younger talent, or the team working on the same page, it is obvious the team isn't playing hard nor bought into the system. The D is the most obvious issue, but the offense isn't clean of this either.
The team needs to be able to make in-game adjustments better. for all of MM's faults, he was good at adjusting in the game to how the other team was playing us. Now, it seems like the other teams adjust...we are still playing off the opening snap script...
And @HarveysWBs nailed it above... There is no gain to firing Barry now. The season is a wash, we still want to attract a quality DC next year, so what we say about the current one publicly has an effect, and these things are better handled inside the locker room instead of the podium. If he gets another shot in 2023, however...