NBA PLAYOFFS : WESTERN CONFERENCE SEMIFINALS : Campbell Arrival Is Timely : Lakers: Dunleavy says he wasn’t ready earlier, plans to use him again tonight against Warriors.

For Laker rookie of rookies Elden Campbell, the NBA required some adjustments.

Like eating habits.

Early this season, he was seen in the dressing room, 90 minutes before a game, munching sour cream potato chips, washing them down with Hawaiian Punch, with a book under his chair titled: “The Thinking Man’s Guide to Nutrition.”

Clearly, this was a young man who was going to find his own path.

“I wonder if his mother knows he eats like that,” Mychal Thompson said.

“It must work. Maybe that’s the key to leaping out of the gym. Maybe I should try it.”

In fact, there is little Thompson begrudges Campbell. The veteran started a lobbying effort late in the season for more playing time for the rookie, even though Campbell’s minutes might come out of Thompson’s meager allotment.

Despite the fanfare, Campbell played little until all issues were decided. In the last three games of the regular season, he got a shot and did well. Magic Johnson joined Thompson in lobbying for Campbell.

Said Johnson: “We haven’t had a pogo stick like that around here in a long time.”

In Game 2 of the West semifinals against the Golden State Warriors, Mike Dunleavy used Campbell for the entire fourth quarter. It began with Campbell scoring six points, taking six rebounds and blocking a shot. It ended with his two fouls leading to the last three Warrior points and the upset.

Barely fazed by the criticism, Dunleavy used Campbell for most of the fourth quarter of Game 4. Campbell had eight points Sunday and is scheduled to be back on the job tonight in Game 5.

What took so long?

Campbell had more to learn than the perils of junk food.

Bewildered at being chained to the end of the bench early in the season, he took little advantage of his few minutes at the end of Laker routs and had to be reminded to stay ready.

“He wasn’t ready in my opinion, and I’m the coach,” Dunleavy says.

“It was very difficult for him to come in. We ask him to play three positions. He has the toughest job of anyone on the team.

“He’s had his ups and downs. He started out strong in training camp, but when we got off to a bad start, I went with my veterans.

“When I made the change in the starting lineup with Sam Perkins, I wanted to keep A.C. Green’s minutes up, as though he was a starter. When Elden didn’t play, he regressed.”

Says Campbell: “It’s tough, always sitting there. I just wanted to play. I thought I could contribute. I guess it didn’t matter what I thought. I just had to stay ready.”

A graduate of Morningside High in Ingelwood who sat in the Forum’s cheap seats as a youngster, he has just graduated from the best seat in the house. All it took was the eternity of his rookie year.

Laker Notes

The Lakers take a 3-1 lead into tonight’s game and will try to close it out. Said Coach Mike Dunleavy: “Any time you have a chance to put somebody away, you’ve got to go out and try to do it. We can’t have any letdowns. We don’t want to go back to Oakland.”

Vlade Divac missed practice Monday with flu but is expected to play tonight. Divac has averaged only 18 minutes a game in this series. . . . The NBA announced that a Laker-Blazer series would start Saturday in Portland if the Laker-Warrior and Portland-Utah series are over by Thursday. Like the Lakers, the Blazers will try to end their series at home tonight.