It took the Washington Bullets nearly 2 1/2 quarters tonight to realize that the National Basketball Association season had started but, once they woke up, they did away with the weak Detroit Pistons, 95-85, at the Silverdome.

Elvin Hayes tried only one shot in the first half and missed it, and Bob Dandridge missed all six of his first-half attempts early in dealing with Detroit's pressing, trapping defense.

The Bullets fell behind by 15 points midway through the third period before Kevin Porter got them going.

The young Pistons were worn down by the bigger and more experienced Bullets and the visitors were in complete control the final quarter.

Porter led the Washington scorers with 21 points. Wes Unseld, Kevin Grevey, Greg Ballard and Wes Matthews chipped in with 12 apiece, while Greg Kelser led the Pistons with 24.

"We've still got a lot of work to do," Unseld said. "Everything out there is still foreign to us and it showed. We can't come back like we did tonight against everybody. We certainly can't Saturday."

The Bullets' home opener Saturday at Capital Centre is against the Philadelphia 76ers, a team that beat them seven out of eight meetings last season.

"This was an ugly game tonight and we just didn't look good," Unseld added.

Coach Gene Shue, who preached defense in training camp, credited the defense for the victory tonight.

"We survived an off-night shooting by playing tough defense," he said. "For us to be effective, we're going to have to do that every night. We would have liked to have gotten out and run more, but we just couldn't. I think we were able to wear them down, though, and by the fourth quarter we were pretty much in control."

The Pistons, under new Coach Scotty Robertson, came out pressing and trapping from the beginning and it bothered the slower Bullets. Washington trailed by a point at the end of the first period and by nine, 48-39, at the half.

Detroit opened the third period with an 8-2 spurt, with John Long scoring six of the points, and moved on top by 15 points, 56-41.

That's when the Bullets snapped out of their doldrums.

Porter led them on a 13-0 scoring spurt and the Pistons were never able to recover. Porter had five points and two assists in the run.

Dandridge tied the game at 60 on a pair of free throws with 3:17 left in the quarter and the Bullets went ahead by three on a free throw by Matthews and a fast-break slam-dunk by the 6-foot-1 rookie.

Matthews had an impressive debut. He made five of 10 shots; four of them were dunks.

Shue wants the Bullets to run on offense and they were releasing the guards once the Pistons put up a shot. That strategy resulted in a lot of breakaway baskets.

The most impressive one was turned in by Matthews. He took an over-the-shoulder pass from Unseld on the dead run and, as he went up for the shot, 7-foot Paul Mokeski and Kamikaze Ron Lee went up with him. Matthews hung in the air, did a 360-degree turn as the two Pistons flew by, and laid the ball in as he was fouled.

As brilliant as he was on some plays, Matthews made some typical rookie mistakes on others. He had Shue cringing once when, on a three-on-two fast break, he tried a behind-the-back pass that was intercepted.

Shue went with a Porter-Matthews back court for a while, too, and expects to use it on other occasions.

The Pistons won only 16 games all last season and haven't improved much. Their playmaker is 6-2 rookie Larry Drew, who went one for six and had four turnovers. Detroit was also without its best offensive weapon, Bob McAdoo, who has a pulled stomach muscle and is on the injured list.

"McAdoo adds a lot to our team," Robertson said. "First of all, he's a scorer and, secondly, he's 6-10 and he's going to get his share of rebounds and, finally, he draws people on defense and that opens up other things for our offense. But I don't want to hide behind McAdoo. Forget McAdoo.