
Interviewing with several people to get a feel for personalities.
Sadly, the worst part was also the best part: the people. There are a lot of good people here. But throw in a mid-level manager that doesn't hear the team crying out under too much work, and it destroys morale.
Some teams seem to work well together, others have team members that are burned out and disinterested in delivering great work, and instead deliver mediocre work needing rework. One such member affects the speed of the rest of the team that is still engaged and trying to move quicker.
Stop overloading your best employees. Let them be able to disconnect after the end of the work day. They can't if they're supporting too many projects, which mean days full of meetings, so the work has to get done at night. Hire more. Listen when they ask, week after week, when help is coming.