Hugs and handshakes abounded at Atlanta United’s training session on Tuesday morning. And with good reason: now-former Atlanta United midfielder Julian Gressel was making the rounds in Bradenton, Florida, offering his bittersweet goodbye to the only professional teammates he’s ever known.



In just a couple of hours, he’d board a plane headed for the nation’s capital. There, he’d slip on a new jersey with familiar colors, trading the red-and-black stripes of Atlanta United for the black-and-red colorway of conference rivals D.C. United.



At this moment in Bradenton, though, the 26-year-old was busy tying up loose ends, one by one. When he found himself face-to-face with Josef Martínez — a player who has thrived on Gressel’s service and one who helped elevate the German’s game to great heights — he grew pensive. Some goodbyes are harder than others.



The exchange was still weighing on Gressel as he...