BOSTON — Joel Embiid shook his coach’s hand and pumped his fist and then half-walked, half-limped toward midcourt and wrapped his arms around Jaylen Brown. He pulled the Boston Celtics superstar in close and whispered something into his ear. Soon, his son was in his arms, and the cameras were all around him and he was smiling and shrugging and trying to make sense of the most improbable and ...