DALLAS -- During their otherwise glittering 6-1 start, the Mavericks at times exposed something of an Achilles heel: Interior defense. Especially when rookie Dereck Lively II wasn’t on the court. On Wednesday night, Toronto came to American Airlines Center and an ill Lively did not. That wasn’t the only reason the Raptors powered their way to a 127-116 victory, but the night’s events certainly…