For stoner to catch up, he'd have to go on a tear reminiscent of last season while the others in front of him took points off of each other. 8 wins take 40 points off of anyone. In some ways it's easier to fight back against 3 strong competitors, if in fact he does have the most pace. With no one head and shoulders out in front, wins add up more.
If it was just rossi 41 points clear of a second-place stoner, that'd be a far taller order.