Maybe. But he certainly didn't dominate them in the decisive game in last year's playoffs. They were kids last year too.
And he had one of his worst starts of the year this season in one game against the Cubs (11 hits and 2 walks in 4.1 innings).
He is certainly capable of dominating (anyone at any time), but your theory here is pretty flimsy. He probably knows that the last two times he's faced the Cubs he's gotten shelled.