He was sitting just feet away when former Knicks star Charles Oakley was surrounded by security officials at his seat, shoving them away before being handcuffed and arrested while watching a game in February.
Even before that, the tennis great had begun to lose patience with his favorite team.
"It's like a total train wreck," McEnroe said.
The low point during a miserable 2016-17 season came when Oakley was dragged out of MSG in the first quarter of a game against theLos Angeles Clippers. A fan favorite as a player, he had fallen out of favor with the organization in retirement after critical comments about the team and MSG chairman James Dolan.
McEnroe, who often travels for his tennis or other obligations, wasn't aware of the history between Oakley and Dolan.
"I didn't even realize at the time that Charles had said bad things about him," McEnroe said. "I hadn't been up on that, so it wasn't awkward for me when he sort of poked me in my back, Charles, right before the incident happened. I was like, 'Hey Charles, how are you? This is my son, Kevin.' He was with me.
"So I didn't put 2 and 2 together and I didn't know what had happened or really what had transpired," he said. "So maybe Jim was already uncomfortable because of past history or whatever and then when Charles and the security guys started to go at it, even before they started to come up to him I was like, 'Uh oh, this is not going to go well, at all.' "
McEnroe is clearly visible in replays of the skirmish that were shown that night and throughout the next day.
"To see Charles Oakley have handcuffs put on him was horrible. Like, I was sick to my stomach, as well as almost every other fan that was in there watching this as it took place," McEnroe said. "I bet you Jim Dolan -- this is just my opinion -- had to feel terrible about what that was."
McEnroe grew up in and still lives in New York, and considers MSG his home arena. The inside cover of his new book, "But Seriously," is decorated with ticket stubs from games and concerts at the arena, including a Knicks playoff game. But like many Knicks fans, he's getting fed up with what he sees.
"I mean I've been a Knicks fan since I was a kid, so this is just getting beyond belief," he said.
McEnroe has owned a home in Malibu, California, for more than 30 years. He often trained in Los Angeles as one of the world's top players during the early-to-mid 1980s, befriending Lakers executive Jeanie Buss and Linda Rambis, whose husband Kurt played for the great Lakers teams of that era that were led by Magic Johnson and Kareem Abdul-Jabbar.
"Watching this was like, I'm sitting there going, why the hell am I a Knick fan again?" McEnroe said, "because this is just absolutely unbelievable, watching Showtime."
Dolan hired Phil Jackson, who won five titles as Lakers coach, as Knicks president in 2014. But the team has missed the playoffs every season under Jackson, who feuded with Carmelo Anthony last season and didn't speak to reporters at all while the team went 31-51.
"I mean, he's known as the Zen Master, like a master talker, and then he's not talking to anybody," McEnroe said of Jackson. "So this whole thing seems to have gone completely off the rails."
Jackson is still hoping to trade Anthony, who has a no-trade clause. McEnroe said he was never the biggest fan of Anthony's game, but that the All-Star forward didn't deserve the treatment he received last season.
"It's crazy to treat a guy that way," McEnroe said. "It seems like, even if it would be better for both guys if they weren't there -- the Knicks and him -- the whole thing just seems, I can't believe how bungled this has gotten."
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