Hamidou Diallo hasn’t played an organized basketball game since his final one with his Connecticut prep school, Putnam Science Academy, at Florida’s IMG Academy four days before Christmas. That was nearly five months ago. Diallo, a highly recruited swingman from Queens, didn’t play a single game for the University of Kentucky after enrolling there in January. And this week he did not compete in 5-on-5 play at the N.B.A.’s draft combine here. So why does his stock appear to be on the rise ahead of next month’s draft? The master of the one-and-done, Coach John Calipari of Kentucky, thinks he understands the thinking. “They don’t know,” he said. “Well, don’t show them. They all like you without watching you. Good. The more you don’t play, the more they like you, the more they’re impressed.” Continue reading the main story “If someone takes him in the lottery I will retire. Four months, doesn’t play, lottery pick, I’m done. I’m stopping,” he said. The N.B.A. stopped allowing players to go straight from high school to the league beginning in 2006, effectively forcing players to attend at least a year of college before turning pro and creating what became known as the “one and done” rule. Calipari has become the acknowledged master of the rule; he has produced 18 one-and-done players during his time at Kentucky. He also has coached several No. 1 picks, including Anthony Davis and John Wall at Kentucky and Derrick Rose at the University of Memphis. But with Diallo, a 6-foot-6 swingman who posted an eyebrow-raising 44 1/2-inch vertical leap here, he may outdo even himself by coaching a so-called none-and-done.