Jayson Tatum says he doesn’t understand eschewing mid-range jumpers, which analytics have shown are typically less efficient when other shots – 3-pointers and shots at the rim – are available. He subscribes to decades of basketball orthodoxy reinforced by his own experience at the highest level of college basketball and the praise heaped upon him at summer league. “Some of the best players ever were great at mid-range,” Tatum said. “Kobe, Michael Jordan, Paul Pierce, Dirk.” Ever since the Celtics drafted Tatum No. 3 last June, Boston coach Brad Stevens has tried to deprogram Tatum’s attitude on jumpers. Tatum heard from Stevens during the summer. “If I was involved in a film session at all this summer, it was about what a good shot looks like once you get to the NBA,” Stevens said. Tatum heard from Stevens during training camp. “If I would pass up a 3 to take a mid-range 2, he’d stop practice,” Tatum said. And Tatum has heard from Stevens during the regular season. “We have tried to make it an emphasis to don’t hesitate to shoot, right?” Stevens said. “He’s so tall that, on the catch, he can get that shot off. And probably his inclination has probably always been to fake it and drive it. But he shoots it with ease and feels good every time he shoots it.” Somewhere along line, Stevens’ message got through. Tatum has taken more than twice as many 3-pointers as long 2s. The change in Tatum’s approach is an overwhelming victory for smarts over stubbornness. Simply by changing his shot selection, Tatum has become much more valuable to Boston. It doesn’t hurt that he’s making a stunning 51.5% of his 3-pointers, either.