The Celtics’ win over the Mavericks at TD Garden last Wednesday night was the highlight of the trip for Atalanta’s group. “We’d love to have Jaylen Brown playing striker for Atalanta, for sure,” Congerton said. But the meetings at the Auerbach Center probably were the most useful. In addition to watching the Celtics practice, the Atalanta crowd met with front office members, coaches, players, and performance staffers in search of any morsels they could take back to Bergamo, which sits about 25 miles northeast of Milan.