PHILADELPHIA — Jayson Tatum knew it when he saw it. When Donte DiVincenzo fell to the floor early in Saturday night’s game between the Minnesota Timberwolves and Denver Nuggets, clutching at his calf, Tatum knew what he was looking at, because it was what he went through a year ago.  “I was definitely sick to my stomach yesterday seeing them go down cause I know exactly how he's feeling,” Tatum said after his Boston Celtics beat the Philadelphia 76ers in Game 4 of their opening-round series. “I know exactly what he has to go through.” DiVincenzo ruptured his right Achilles tendon, and immediately followed Tatum’s critical first step of undergoing surgery the next day. The team announced DiVincenzo had flown to New York to see the same surgeon Tatum did, Dr. Martin O’Malley.  “I’m glad he got his surgery today,” Tatum said. “My thoughts and prayers have been with him.…