They won 43 games last year. You don't think Lance Stephenson, Noah Vonleh, and their young group of MKG, Cody Zeller, and Kemba Walker coming back could notch them 7 more wins?
43 wins to 50 wins is a big jump. That's harder than jumping from 36 to 43 wins, for example. Likewise, jumping from 50 to 57 wins is more difficult than going from 43 to 50.
I don't think it's realistic to expect Vonleh to be an immediate contributor. He may turn into a really nice piece in time, but he's not playing major minutes out the gate.
MKG and Cody Zeller look like role players, and while Walker is a nice young player, he doesn't appear to be a star either. Those guys can and probably will improve, but they're likely not going to make the huge year-to-year leaps that young stars make.
Stephenson is a big addition. For all of his baggage, he should be a net positive, but he's not a perfect fit on that roster. Last year Charlotte was shockingly good on defense but absolutely putrid on offense. Lack of spacing was a major issue, and that's exacerbated by the loss of McRoberts--he's not a sniper, but he's an above average outside shooter for a PF. Marvin Williams may alleviate that if he's a full-time PF, but he's nowhere near the passer that McBobs is, so that's going to hurt their ball movement. Stephenson will give them some more juice as another creator on offense, but he's also a mediocre 3-point shooter, so he's not helping them spread the floor for Big Al.
Also, as WT pointed out, a lot of teams in the east got better. Lebron's move to Cleveland results in one less punching bag in the conference. The Bulls added Gasol. You cite Charlotte's internal improvement with Walker and MKG, but Washington is going to get even bigger boost from the improvement of stars like Wall and Beal. The Pistons may still be bad, but SVG should give them a bump. I'm not sure that anyone got significantly worse, aside from possibly Indiana (though if the Pacers get out of whatever funk that was in the second half of the season, they'll be fine) and Brooklyn (if Lopez stays healthy, that may help offset the loss of Pierce, plus they won't have a rookie coach learning on the job).
It wouldn't completely shock me to see Charlotte get 50 wins, but I think the odds are well below 50%.
