When John Isner first got to town for his Miami Open title defense, he went for a practice session at the old tournament site in Key Biscayne instead of the new location at the stadium used by the NFL’s Dolphins. It wasn’t that he wasn’t sure where to go, of course. Nor was he trying to soak up the good vibes at the place where he won an ATP Masters 1000 trophy for the first time. “It was just about convenience. Close to my hotel. I just wanted to break a sweat and went out there,” Isner said Tuesday.