I think 2/3 defenders are easy to come by. Green is good. Holiday was had for nothing.
The reason our defense is so bad is
1) We have no defensive anchor (center)
2) Kidd is an @#@% and no one is working as a team to defend
We can fix #1 by just getting a starting center. Then again, the FA list sucks. Vuc is awesome, but he's not a defensive guy. I wanted Poeltl who can do both, but he wanted to go to Toronto and he will almost definitely sign there. We couldn't afford him anyway without letting a lot of guys (maybe Kyrie) walk.
https://www.spotrac.com/nba/free-agents/center/