I haven't seen any evidence that Kingsbury can't lead a successful NFL offense. Each week we've seen some wrinkles that if the players just executed the average player better, would put this team over the top.
The problem is that Murray is not ready to be a good, starting NFL QB, and the current team is very much dependent on him to be a good QB now.
The Cardinals will take their lumps, and if they can develop some of these young skill players and add to the roster, they should be much better next year.