This is stuff that everyone knows, but I still want to type out the reasons that the Kings have transformed from a all-O no-D team to an all-D no-O team--at least that's the way it's been so far, 5 games into the season:
1. Peja-Artest trade, and the changing of the guard in general
Defensively, Peja was actually quite decent and often underrated, but obviously he's no Ron Artest. Artest's intensity probably rubs off on teammates as well. His impact was most obvious when the Kings vastly improved defensively last season since the trade. Offensively, the Kings lost a big part of the Princeton, which the Kings were still running early in the season, with the Peja and Christie trades. Artest's inefficiency so far in the season coupled with the total volume of shots he's jacking up makes it very hard for the Kings to be a good offensive team--if Kevin Martin hadn't stepped up his game, the Kings offense would've looked even worse. Offensively, the Kings have been league leaders in most assists and least TOs all throughout the Princeton era, while this bunch of Kings have really struggled with turnover problems and passing in general, which I think should partly be attributed to getting used to new personnel, and partly to just the fact that the new players aren't as good ball handlers and passers as members of the old guard.
2. Replacing Adelman/Carril with Musselman
I think the end of the Princeton era was more dictated by the change in player personnel and not the coaches, really--Adelman was already phasing out much of the Princeton late last season. So offensively, I really think that the struggles has little to do with Musselman, but simply has to do with Artest's inefficiency and Bibby's struggles with his shot, which probably has to do with his injury, as well as the lack of Brad Miller. The biggest difference Musselman has made, in my opinion, is in the team's overall hustle and effort, best exemplified in Bibby's improved defense and improved team rebounding as a whole. A lot of defense has to do with intensity--and this team has certainly stepped it up on this front.
3. Brad Miller's injury
Brad Miller is still one of the most effective centers on the offensive side of the ball, and the Kings really do miss his overall ability to shoot and stretch the defense, as well as his ability to handle and pass the ball from the high post. Defensively, SAR is a very good post defender despite his lack of size when played at the 5, and the SAR/KT combo is a better defensive and rebounding combo than when Brad Miller is on the floor.