It is not easy to go on a long winning streak, and even harder to pull one off that manages to go into double digits to start the regular season. The Cavs have roared out of the gate to do both, causing NBA fans and analysts alike to begin asking if Cleveland is really a legit threat to Boston in the East.

Mitchell didn’t play in the final two games of last year’s Eastern Conference semifinals, when the Cavs were eliminated in five games by the Celtics, who went on to win another championship. Allen missed that entire Boston series with a broken rib and ...