The Knicks emerged from the All-Star break last night as flat as one of their depressing January games, falling behind 61-49 at intermission with the Cavaliers scoring the most first-half points they had all season. Then de facto leader Tyson Chandler took over the locker room and let the Knicks have it. "I didn't want to lose to these guys,'' said Chandler, who had 13 points, 15 rebounds, four blocks and three steals.