I agree we're going to miss Luke, but I'm not sure on the details to know how much of this lies with Coach Crean.
From what I know, Coach was taken off guard by Luke's departure and it might have been too late to fix.
I guess the underlying rule is everything falls under the coach and it's his job to know and fix it.
Coach Knight let one of the greatest players of all time leave the program and he admits it was one of his biggest mistakes. From what I've read, I believe Coach Knight left that responsibility to the upperclassmen, which I believe has been part of our issue the last couple years. (lack of upperclassmen)... but clearly that model failed sometimes too.
This team would be a lot different with Luke, but Coach Dale said it best:
"I would hope you would support who we are. Not, who we are not. These six individuals have made a choice to work, a choice to sacrifice, to put themselves on the line 23 nights for the next 4 months, to represent you, this high school. That kind of commitment and effort deserves and demands your respect. This is your team."
Another Coach Dale quote that's relevant to this team "I've seen you guys can shoot but there's more to the game than shooting. There's fundamentals and defense."