Yes, Lukaku had a poor game today, but to say he's not good enough for United is ridiculous. Have people forgotten how much he progressed last season?
At the beginning of last season his all-round game was lacking despite banging in the goals, whereas (after a mid-season slump) he came back really strongly from around Feb/March time onward, not only scoring plenty of goals again, but also showing immense improvement in his link-up play, dribbling, and crucially his mentality. It seemed to dawn on him that he had to cut the mustard every time he steps onto the pitch in a United shirt, and this was reflected in both his increased work-ethic and willingness to be a leader that became more evident as the season wore on. His big game performances were improving too, though he still needs to find the back of the net in more of them.
Lukaku is the least of our problems. Wasn't it just a few weeks ago that people were creaming over his World Cup showings? I seem to remember him having a phenomenal game against those international also rans called Brazil.