John McEnroe is so full of it.  There was never any shortage of people telling and showing him in every way possible that this behavior was out of line.  He didn't listen because he didn't want to listen and he didn't want to change.

Nothing tennis had done differently would have changed that - he's just never going to grow up and stop blaming everyone else for his actions.

From The Age: McEnroe swears change was possible

JOHN McEnroe says he wished someone had kicked him out of a tournament for his bad behaviour earlier in his career — as he was in the 1990 Australian Open for swearing at a chair umpire.

McEnroe said that until his Australian Open experience, not only was he not aware his behaviour often crossed the line into the unacceptable, he did not even know there was a line.

Sixteen years ago, in a fourth-round match against Mikael Pernfors, McEnroe, the brilliant but hot-tempered tennis superstar, was thrown out of the Australian Open after he directed a series of profanities at the officiating chair umpire — then at the match supervisor and then at the tournament referee.

McEnroe, who was 30 at the time, wishes a tournament had had the courage to take such an action when he burst on to the professional tennis scene as a precociously talented 18-year-old in 1977.

"If someone had done that to me when I was 18, I honestly think a lot of things would have been different," he said. "The message I got early on was that I could get away with just about anything on the court.

"No one wanted me defaulted. The tournament director didn't want me defaulted, neither did the TV people. But if someone had nailed me, cost me a big tournament, the chances are I would have learned my lesson and not done it again.

"I mean, I'm not stupid. Tell me where the line is and I won't cross it. The message I got until Australia was that there was no line."

Comments

This goes against what he said in his book "You cannot be serious". In that he says that he always knew where the line was, and he knew the number of offences he could get before he was defaulted. Before the 1990 AO the ATP changed the number of offences you could rack up in a match before you were defaulted. He says he was not aware of this change, and was therefore surprised when he got defaulted because he thought he had one more offence before that happened.

I agree with both of you.

If he had been defaulted earlier in his career it would have given him something more to complain about. There's no way that getting defaulted prior to the 1990 AO would have changed his behavior. He was still acting like an ass after that default, it didn't change him then and it wouldn't have changed him before.

Mac could control himself if he wanted to - witness his matches against Bjorn Borg where he never acted out.