For the first time in a month, the Washington Bullets looked like an ordinary team tonight. It couldn't have come at a more inopportune time.

The Detroit Pistons wore them down at the Silverdome, handing the Bullets only their second defeat in the last 11 games, 107-96. At the same time, the fading New York Knicks were being defeated by the Boston Celtics, 102-98. A Bullets' victory would have enabled them to move into a tie with the Knicks for the sixth and final playoff spot in the Eastern Conference.

Instead, the defeat leaves them still a game behind with only six left to play. Fifth-place Atlanta (40-37) was idle tonight, so picked up a half- game on both the Knicks (39-37) and Bullets (38-38).

All three will be back in action Friday. The Bullets will visit Boston, Atlanta will be at home against Chicago and New York will be host to San Antonio.

Because both the Knicks and Hawks won the season series against the Bullets, Washington must finish ahead of one of the two to make the playoffs. A tie won't help them.

The Bullets were outrebounded and had more careless mistakes in this one game than they have in the last week, and their bench, which has carried them through some hard times, was outscored tonight, 45-8.

The Pistons had the unlikeliest of heroes as reserve forward Ray Tolbert scored a career high 20 points and had 13 rebounds and four blocked shots and third-string center Tom Owens had 10 points and nine rebounds. It kept the Pistons' slight playoff hopes alive.

Washington made up a 10-point first-quarter deficit and led, 47-46, with 70 seconds left in the half when they fell asleep. The Pistons scored eight straight points, six of them from the foul line.

Tolbert started the rally with a free throw and then Frank Johnson had the ball stolen by Isiah Thomas and then fouled Thomas. The Detroit guard made both free throws. On the Bullets' next possession, Ricky Sobers, trying to go one on one, had the ball taken from him by Tolbert and Kelly Tripucka got a fast break out of it.

The next time down the floor, Johnson missed a jumper with two seconds left, but Carlos Terry committed a loose-ball foul and Vinnie Johnson made two more free throws.

Owens intercepted Jeff Ruland's inbounds pass and was then unwisely fouled by Terry as he (Owens) heaved the ball at the basket from 70 feet away. Owens made one of two free throws and the Pistons led, 54-47, at halftime.

The Bullets made only eight of 28 shots in the third period (29 percent) and there went the game. Detroit led by as many as 22 in the final quarter.

"That one stretch at the end of the half killed us," said Bullets Coach Gene Shue. "It killed us because we were careless and then no one could put the ball in the basket in the third quarter.

Ruland started tonight and, even with his sore wrist, played 47 minutes and added 13 rebounds to his 23 points. But he got virtually no help on the boards. Rick Mahorn had only three rebounds and the Bullets were outrebounded, 54-43.