The men's locker room at Wimbledon has undergone its own metamorphosis as John McEnroe's fellow players watch him this week. The thinking was that after Tuesday' $1,500 fine for bad behavior, the first assessed a player in the 104 years of the tournament, McEnroe could not possibly do an about-face.

But he did. Wednesday, he played an uncompleted second-round match against Mexican Raul Ramirez and didn't say one word, kick his racket or throw a tantrum.

Sitting in front of his locker today before completing his defeat of yramirez, McEnroe sought to tune out everything and everybody by listening to rock music on a cassette. He was not his unual jovial self. The official reprimand from Wimbledon seemed to have had the desired sobering effect.

Now we all wonder how long it will last.

The press here has been very tough on McEnroe. "Throw Him Out" and "Disgraceful Lout" were some of the headlines following his infamous first-round match against Tom Gullikson.

Today those same papers read "choirboy," "angel" and "Little Lord McEnroe." And through it all, McEnroe walks that thin line between determination and despair.

Comments from colleagues about his current Dr. Jekyll and Mr. Hyde act border on the cynical.

Peter Felming, McEnroe's doubles partner: "John can't play when he's bottled up. I've never seen him so down. But he wants to win this tournament. A win here would be very gratifying for him."

Sherwood Stewart: "The writing is on the wall. It sure doesn't help all your contracts if you can't play Wimbledon or if you get had publicity here. He's got a new racket contract with an English manufacturer (Dunlop). hYou think Dunlop's not worried?"

Johan Kriek: "There is no question that your business deals are affected by your performance at Wimbledon. (Bjorn) Borg doesn't make $2 million a year in endorsements because he wins five Tournaments in South America. This title here is bigger than any player; always will be. John knows he's got to behave."

Still, McEnroe couldn't help getting in a few digs. He assumed an unrepentant air during his postmatch interview. He was glibly quotable and sometimes inadvertently contradictory.

A few of McEnroe's remarks:

"You've got to roll with the punches."

"I've got to find a happy medium."

"It's harder now for me to win because I can't be myself."

"The papers here always write lies. They're not fair to me at all."

This last comment referred specifically to a report on BBC television Wednesday evening that McEnroe got a warning from a traffic policeman for speeding. It was reported that he was told to appear before a judge to answer the charge. However, McEnroe was not driving the car, Fleming was McEnroe was only a passenger.

"I've never driven any car of any make in England," McEnroe said. "I've never driven a car in my life here because I'm not used to driving on the left side of the road."

John McEnroe Sr. feels the furor over his son's behavior this week will hurt him in the future. Sounding like every inch the New York Park Avenue lawyer that he is, he said, "The Wimbledon committee has manifestly overreacted. I'm not saying that John should not have been fined or penalized. But this business about a future $10,000 fine for more aggravated behavior' is nonsense. There are procedures for that. That committee has clearly overstepped its properly defined bounds."

And as if to underscore his family's concern, John Jr. refused to given an interview today to the BBC. "When they begin telling the truth I'll start giving interviews," he said.

I thought McEnroe should have been fined. But I think the Wimbledon committee went too far in regards to what it would do next if John misbehaved again. The committee should have waited rather than threaten.

Still, something like this will make McEnroe take notice because it took place at Wimbledon. That makes it acceptable to slap John McEnroe's wrist.