Elvin Hayes admits that sometimes, when Kevin Porter's name is mentioned, he wonders what would have happened to the Bullets if their playmaking guard had not been traded away after the 1975 season.

His conclusion is always the same. "We would have done pretty well if he had stayed," said Hayes. "Good old K.P., how he can pass the ball. He's some kind of player."

But K.P. is now a New Jersey Net, after a two-year stint with the Detroit Pistons. Hayes and his teammates will be searching for ways to control him today in a 1:45 p.m. NBA game at Rutgers University in Piscataway, N.J.

The first time the teams met this season, Porter had a feast. He scored 30 points and added 17 assists as the Nets stunned Washington, 106-95, at Capital Centre.

It didn't matter who guarded him that day, Tom Henderson, Larry Wright or Phil Chenier. Porter pranced in stutter-step past all of them and then challenged the giants underneath with so much success that he took control of the game.

"We can't let him do that again, although it's not uncommon for him to run things," said Bullet coach Dick Motta. "But you know he'll be sky high for this one. We've got to keep him off to the side and not let him to down the middle. We tried it last time and it didn't work."

Henderson agrees with that tactic. "I want to make him go to the baseline and not penetrate," he said. "He just had a good night the first time. It was one of those things. We just have to be ready to play him better and we will."

Of all the Bullets, Henderson probably feels the sting of a good Porter performance the most. He realizes fans have to wonder - just as Hayes wonders - how good Washington would be if Porter were still around.

"You can't think back on those things," said Bullet general manager Bob Ferry, who made the trade. "You could put together a whole list of people we have traded and probably come up with a good team. But you do what you have to do at the time to make the Bullets better."

When the Bullets traded Porter for Dave Bing, it was a matter of the team not being able to wait for the player to mature. Although Porter led the league in assists in 1975, when the Bullets made it to the NBA final, he also was the league leader in foul disqualification.

Ferry says K. C. Jones, then the Bullets coach, was uncomfortable depending on a foul-prone, temperamental guard to fill the key playmaker role. Both men felt the team would profit with a more experienced, less emotional leader like Bing. Especially since the club's only other ball handler, Jimmy Jones, had been slowed by a knee injury.

Bing reitired at the end of last season only to sign with the Boston Celtics shortly after this season began.

Porter said it took him two years to realize that the raps against him - "I couldn't control myself and I lost my temper" - were true. Since then, he has worked hard to change his image and the fruits of that labor are showing this season.

He has fouled out of only two of 37 games this season, averaging only three fouls a contest. He still is as competitive as always but he doesn't let himself fall into blind rages like he did so often in 1975.

As a result, he is playing more (39 minute a game with New Jersey) and is averaging more points (17 a game) while dashing out nine assists a contest, second in the NBA to John Lucas of the Houstan Rockets.

"I think I've become a better player," said Porter. "But after six years, you should be better. I just try to do what I have to take advantage of the talents on our team."

The Net's most obvious talent, besides Porter is rookie Bernard King, who is averaging 25 points a game. He scored 21 points in the first meeting between the clubs despite the close guarding of Bob Dandridge.

Dandridge won't be in the best of shape for the rematch. He has a sore knee, which he treats with ice after games. So far it hasn't cut into his playing time, although until a 29-point outburst Friday night against Indiana, he had been in a shooting slump.

"They hurt us last time with their zone," said Motta," and with King and Porter. But we are getting smarter. We picked against the Indiana zone very well. I think we'll be ready for them this time."

Jan Van Breda Kolff, who stands 6-foot 8, has been starting alongside Porter at guard since Bob Carrington was injured ... Guard Ed Jordan has average 10 ponts a game since joining the Nets from Cleveland. He backs Porter ...