WELLESLEY, Mass. — No one gets punched in the face during regular training at the Harvard Boxing Club. But this was fight night, and the jabs, hooks and uppercuts were suddenly very real. Boxers passed the time before their bouts by meditating, jumping rope or punching at mirrors. Amid this commotion, Ryan Jiang, a Harvard University freshman, sat alone on the floor. He was on his phone, watching a sparring video he had found of the boxer he was scheduled to fight that evening, trying to learn something, anything, that could help him in their match. “He throws a mean right hand, that’s what I’ve learned,” he said ruefully. Jiang is a self-effacing 19-year-old, weighing about 160 pounds, and studying applied mathematics. He awoke the morning of the fight with a racing heart. “I’ve been nervous all day.” His opponent, Colin Brazas, a senior from the Babson College Boxing Club, was across the room, pounding his right hand into a heavy bag, making thuds like someone beating a rug with a bat.…