the bottom line is that all the upper classmen or anybody with a lot of playing time/experience shouldn't be making more than a few unforced errors. they should know the 'margins of error' in any aspect (like passing) by now. individual matchups, strength and weaknesses of opponents, styles, will always cause fluctuation, but if you aren't consistent on fundamentals of whichever ideology/s are being coached then it will show in individual and team results.
i don't have the answers, but i can only suggest the staff needs to continually simplify the game/central roles for certain players, maybe limited to just a one or two things in each phase (halfcourt O, halfcourt D and transition).
i'm naive about how practices are conducted so this may be bunk: for example, do we sometimes play 5 on offense and say, 6 or 7 on defense and concentrate on the fundamentals such as passing, timed transition, over and over without even shooting the ball? just a thought.