I'm not really in the habit of defending Keith Smart but I can all but guarantee that what actually happened on the court bore little to no resemblance to what he tried to implement in practice or draw up during games.
Part of that blame has to fall on the players but if what you are preaching isn't getting executed that falls primarily on the coach.
For players to buy into any system they have to (1) have faith in their coach (2) experience a consistent message and and (3) be given appropriate roles (4) see positive results from the system
Smart failed on all accounts. The team was losing, players were jerked in and out of the lineup with everyone given the green light to shoot early last season and Smart said one thing and then did another constantly. Not surprisingly he lost the locker room and destroyed any goodwill he'd established the previous season.
Yes, the actual schemes on offense and defense (as well as matchups, adjustments, substitutions etc) are hugely important but there is so much more that goes into being a successful coach, much of it how you relate and deal with people. Keith Smart showed he's simply not NBA head coach material. So did Musselman, Natt and to a lesser extent Theus. I have more faith in the Malone hiring than I've had in any Kings head coach since Adelman, but we still have to wait and see what with him as well.