Antoine is clearly the most unpredictable point forward in the league.
That's his X-factor. Next, with KG around, and the Celts now a rebounding squad, 'Toine misfired, jacked up threes can be kept alive in a manner which will make it difficult for teams to adapt to the C's. Realize, opposing teams will be looking for him to pass it off to Ray Ray, KG, or Sam, half the time. In a sense, that's what a Tony Allen would do if a slash to the basket wasn't available for him. In Antoine's case, he'll heave a shot and perhaps, a third will go in; the other two thirds will be Celts offensive rebounds thus creating a second opportunity but now with, the opponents defenses eyeing 'Toine instead of let's say Sam. All and all, it works but in a limited fashion.