The team is soft to begin with but compounds the problem by giving very little effort on defense. Let's name a few names: Olynik, Green, Bass (most nights), Sully (at times), Zeller, Bradley. Some of this group puts in the effort occasionally. But they're also the most consistent slackers.
KO is soft as a grape. He needs a coach who will get in his face and force him to compete on the defensive end - but in the end, he is what he is and they knew this when they drafted him. Green has had a good year - till recently - offensively. Defensively he hasn't hustled all season and when his shot's not falling he's just in a fog. And his shot hasn't been falling for a couple of weeks.
Bass gave an effort tonight - probably because he was out with 4 other guys who were playing defense and didn't want to embarrass himself - but he's been disinterested for too long. Sully's a bit like Bass, except he's also the team's best rebounder and low post scorer so he has to play. Unfortunately because he's undersized he has to outwork the guys he's playing against every night and just doesn't do it often enough.
Zeller is another example of aggressiveness not being in the DNA. Bradley's now looking for his points, pure and simple. This could get a lot worse with Young possibly pushing him for minutes - kind of like he has to justify his contract and veteran status.
The problem is Brad's still giving lots minutes to guys who don't hustle and not forcing the issue - so it becomes a malaise that just sets in.
Best way to solve it at this point is get the vets who won't make the required effort off the roster as soon as possible. The season is already gone. But this is also part of Brad's learning curve as an NBA coach. Hope its not his undoing.