MOMENTS BEFORE THE Milwaukee Bucks were set to take the floor Saturday, the players and coaches gathered inside a tight hallway outside their locker room at T-Mobile Arena in Las Vegas.

It was a familiar stage; they are the only team to reach the semifinals in both NBA Cup tournaments. And remembering how that trip ended one year ago spurred a renewed focus. This year, the tournament has served as more than just a catalyst for a team that started the season winning two of its first 10 games. It just might have saved Milwaukee’s season.

“Forty-eight f—ing minutes,” Giannis Antetokounmpo implored the team ahead of its semifinal. “Keep one another accountable. Somebody missed a shot, pick him up. Make him feel good about himself, so he can make the next one.

“We owe them one,” Antetokounmpo continued, referr...