Tony O'Brien/Reuters
The first day Sascha Bajin was at the U.S.T.A. Billie Jean King National Tennis Center getting ready for this year’s United States Open, he went into Arthur Ashe Stadium and took a quick look around.
He could still feel the atmosphere from a year ago, he said Friday.
It’s been about a year since Bajin was in the Ashe Stadium stands watching the player he coached, Naomi Osaka, win her first Grand Slam title against Serena Williams, whom Bajin used to work for as a hitting partner. It’s been about a year since the coach in Williams’s box, Patrick Mouratoglou, was caught using an illegal hand signal, which sent the match spiraling into chaos.