I think the criticism of WW has gotten a bit extreme. So here's my take on it.
Willie Warren is a super talented offensive player, with the ball in his hands he is one of the most dangerous players in the nation. His ability to get to the basket is superb, and he can get hot and fill it up from outside also. However, he does not know how to score or even be a factor offensively without dominating the ball. He tries to be a unselfish 'team player' sometimes, he won't appear as aggressive, he'll even appear extremely passive on offense. For him it seems like there are two extremes with no middle ground. He either dominates the ball or is an offensive afterthought; he doesn't know how to be involved without the ball in his hands. Not knowing how to be involved, he becomes very passive, which easily looks like a lack of effort.
I think some of the criticism of his effort on both ends of the court is also unwarranted. While he has lacked effort at times, it also seems he isn't the type of player that LOOKS like he is playing hard, even if he is.
You could see these same things when he played at North Crowley HS. In the state semifinal, he appeared somewhat uninvolved, but finished with 19 points. In the state championship game, he dominated the ball much more and finished with something like 27 pts and 11 assists. Back in high school he had the same problems playing away from the ball.
My point in this is maybe its not so much his effort that needs to be questioned all the time. Maybe Warren just has some deficiencies in his game that make it appear that effort is his problem when it really isn't.