Now having said this, Luke wasn't the only reason why the Lakers lost. It takes a team effort to win, and it also takes a team effort to lose. The entire team seemed allergic to defense the entire game, and the fact that they gave up 113 points in regulation is a testament to their lack of defense. Luke contributed to that, but he's not alone in making mistakes.
To suggest this loss is mostly due to Luke is just using him as a scapegoat/whipping boy to make it appear as if there's an easy explanation for the loss and hence an easy solution to prevent future breakdowns against inferior teams.
I don't think anyone is saying the loss rests solely on Luke....but citing him as a contributing factor. That is all. Given his minutes last night, he contributed very little on the floor.
His dropoff in performance seems even more pronounced since Vlad's departure....which is even worse. No pressure for his starting position (people are dreaming if they think Morrison has any shot of replacing him as a starter), and he's slacking even worse.