I’ve had a BA working for me and leading a team. It was one of the highest performing teams I’ve ever had in my org (because everyone was hand-picked/self-selected into that team).
It’s not realistic to build teams like this and this team fell apart/could not be sustained when one of the key members eventually left. But they seemed happy and delivered like crazy.
a) How good he was. Just like really really good quality of work.
b) How bad he was. Crying client. Regularly destroying team morale and productivity with incredible drama.