I really feel people should cut Rozier some slack, he really did have every reason to be unhappy.
In his last couple of years in Boston Rozier demonstrated that when given the consistent playing time he can produce at the level of a quality 2-way starting PG. He's further proven that to be true this season, as he is averaging 17.5 pts (on 43% / 36% . 85% shooting) along with 4.1 reb and 4.4 ast for Charlotte. Those are excellent numbers for a 24 year old PG in his first season as a starter, so the kid has clearly proven he is worthy of those minutes.
Now imagine you are this kid - you know without question that you are capable of being a starting PG in the right situation, and yet you are stuck on a team where you're always the 3 banana behind Kyrie and Smart. Now the year prior it probably was easier to stomach that, because even though he wasn't getting his big role, the team was winning games and overachieving, everybody was getting along, and the overall success an happiness probably made it easy to accept being stuck in a less then perfect role. But last year was different. The team was under-performing, guys weren't getting along, the locker room was rotten - what is there to make a guy like Rozier feel good about staying buried on a team like that when he could be somewhere else spreading his wings?
To make matters worse it was a contract year, so his ability to get opportunities directly impacted his ability to showcase what he could do, which in turn had potential impact on the direction of the next 4 years of his life. That's a big deal.
So all things considered, how can you blame him for being upset with all that factored in? In ihs first 3 years Rozier really ever complained, took what role he was given and took it with pride.
To put things into perspective, I'm 35 and work in the IT industry. My current job is far more basic technically then a number of the jobs i've worked in the past, so where I am I feel extremely limited in terms of my ability to grow. In addition to that I'm actually losing skills, because having a more limited job is actually causing me to forget things that used go be second nature to me in the past - so the role is really holding me back. This doesn't only impact me now, it impacts me in the future because any young person in a career is going to have aspirations to want to move up in the future, and as long as i'm in this job that's not happening. I know I'm capable of much more then the duties i'm being given. Now for me, it's simple. I am not tied to a contract - I can quit any time. Rozier can't. He's stuck to a contract he has to honor, and if he were to try to force his way out - well, we all know how players are perceived when they do that...only stars can get away with it with some reputation in tact. So all he can do is sit there in frustration and bear it. If I had to sit here in this job for 4 years and bear my current role, I'd be every bit as frustrated by the end of it as Rozier was.
I'm not saying Boston was at fault for not giving him a more consistent role or making him a starter. I'm not saying Smart or Kyrie are at fault for taking his minutes. I don't believe that any one person was really at fault. All I'm saying is that it was a really bad situation for Rozier, and I can totally understand his frustration. 4 years is a very long time to for a young kid trying to prove himself to be stuck in a position where you feel like you're being constantly held back and have little control over it. People might try to claim otherwise, but I'd hazard a guess that the majority of people here would feel every bit as frustrated if they were put in his shoes and had to endure that situation for 4 long years.
As for the idea of trading Rozier - I can certainly understand why people might think that is a good idea, and it may well have been. But it's also easy to say that in hindsight, knowing things went. Unfortunately it wolud have been hard for Danny to make that call given Kyrie's free agent status - if Kyrie walked and Kemba decided to stay in Charlotte, Boston may not have had much choice but to re-sign Rozier for depth at the PG spot. I'm guessing Danny wanted to retain that flexibility moving forward to provide insurance against Kyrie's unpredictable mindframe.