It’s always been hard for Malik Mack to hide on a basketball court. Yet after making a pass in early March, in Harvard’s season finale at Dartmouth, the point guard cut through the key and faded to the opposite corner. The defense scrambled to stop Harvard’s fast break. Twenty shoes squeaked inside the quiet gym. Alone, the 6-foot-1 Mack stood in front of his team’s bench, waiting for the ball to swing back his way. And when it did, he caught, rose and shot in a fluid motion, his left hand flicking a three through the net.