The problem with Ross is that when he's having a bad game in terms of his touch, passing etc, its basically like being down to 10 men. If he was struggling but still putting tackles in, harrying, pressing and tracking back then he could be forgiven as players will always have off days, however Ross only offers something in an attacking sense, so if that's not working then we are stuck.
Arsenal have a similar situation with Ozil, when he's off form its like being a man down as he does 0 dirty work. He will lose the ball and expect everyone else to win it back, however Ozil has a lot less off days than Ross.
It not just him, there are a few like him out there, however he needs to take responsibility for the work he's putting in on the field.