In the run-up to Christmas, Kristaps Porzingis, the 20-year-old forward for the New York Knicks, spent an evening signing basketballs and T-shirts at the Brazen Fox pub in White Plains. For 90 minutes, dozens of people — mostly young men in blue-and-orange Knicks gear — approached him and shyly introduced themselves with the same excited greeting: “Yo, K.P.!” Many of them asked Porzingis, who is 7-foot-3, if he would mind standing up before they took their photographs and selfies. What one learns in such a situation is that there are not many ways to tell a man he is tall.