That's just the most frustrating thing about him Asa. The deviation.
When he's good, he scales peaks far higher than Chamakh, Park and Gervinho can achieve. But when he's bad, he reaches Grand Canyon depths. Problem is that he doesn't just have wide deviation, he's also very volatile. So you can't rely on him to have a few good months and a few bad months like Rooney. He's just good, bad, good, good, bad, bad, bad in a string of games and it's hard to predict how he'll fluctuate.
That's why to me, he can only be a 12th man, focused on the specific purpose of stretching the defense.