Knowing when to make a substitution and when not to make one - is probably the most difficult job a coach as once the game has started.

Washington Bullet Coach Dick Motta combines a pregame plan for substitutions with a recognition of when a player needs rest and a sense of knowing when one player's skills are needed more than another's. He is one of the best personnel manipulators in the National Basketball Association.

"When it comes to substitutions, everything is really flexible; it has to be," said Motta. "But I have to have a plan in my mind."

Against the Philadelphia 76ers in the Eastern Conference playoffs, Motta's set plan for substitutions in three-fold. First, he wants to rest Elvin Hayes for approximately three minutes at the beginning of the second and fourth quarters to keep him fresh and strong at the end of the alf and at the end of the game.

Second, Motta wants to rest Bobby Dandridge whenever the 76ers rest Julius Erving because Dandridge is perhaps the only Bullet who causes serious problems for the 76er star.

And third, Motta wants Charles Johnson to play some in the second quarter and he wants him in the game at the end, "because . . . (he) . . . is so smart and always knows what to do. He's a savior. He's like a rose. He brings that sweet smell to what we want to do."

In Sunday's 121-105 victory over Philadelphia that gave the Bullets a 31 lead in the best-of-seven series for the Eastern Conference championship, Motta's pregame substitution plan worked like a charm, as did most of the on-the-spot adjustments he made.

Motta went to his bench first with 3:22 remaining in the first quarter. He brought in Greg Ballard for Dandridge and Joe Pace for Mitch Kupchak, because both Dandridge and Kupchak were tired.

"Bobby asked to come out, Mitch didn't" Motta said.

"I can just tell when Mitch needs to come out. I have no set schedule with him. He wasn't playing all that well at the time, either."

Twenty seconds later, Motta sent in Larry Wright for Tom Henderson because he needed more offense. The Bullets were down by three points at the time and Doug Collins was "chasing," leaving his defensive assignment because he felt Henderson was no threat to score.

Henderson is not a good outside shooter and with Philadelphia clogging the middle, he found it hard to drive. So Collins was leaving Henderson virtually unguarded and chasing the ball, thus disrupting the Bullet offense.

Usually, the 76ers don't chase when Henderson is not in the game unless they are in a desperate catch-up situation.

During the regular season, the Bullets were able to get by without Henderson being much of an offensive threat. They cannot afford it now, and as a result, Henderson's playing minutes have been decreased.

Sticking to his game plan, Motta brought in Dandridge to start the second quarter and rested Hayes.

Three minutes into the period, Darryl Dawkins hit two long jump shots over Kupchak, so Motta brought in Hayes for Kupchak.

"It was a defensive decision, who Elvin came in for," Motta said. "When Dawkins hit those two shots I got a little nervous." Dawkins baskets put Philadelpia ahead by five.

Later in the period, with Philadelphia ahead, 42-33, Motta yanked Wright and put Grevey back in.

"Larry was one for five and he had missed a couple of wide-open shots," Motta said. "I thought he might have been a little tight and it was time for Kevin to come back anyway."

For the final 6:12 of the half and with a lineup of Hayes, Kupchak, Johnson, Grevey and Dandridge, the Bullets outscored the 76ers, 19-4, and for all practical purposes, put away the game.

The three-minute rest Hayes got at the beginning of the period worked wonders for him, as he scored 15 second-quarter points in nine minutes.

In the third period, Motta stuck to the plan he had established in the first half. He started Henderson, and when Philadelphia started chasing, he brought in Wright. When Kupchak tired, he brought in Pace.

"Mitch let McGinnis drive right by him twice," Motta said. "He needed a rest and it helped him when I brought him back later."

Motta also admitted to making one of the two substitution mistakes he made in this game in the third period.

With 3:35 left in the period, Motta put Ballard in for Dandridge - but less than a minute later put Dandridge right back in for Ballard.

"Our game plan is to give Bobby (Dandridge) a rest whenever Dr. J (Erving) comes out," Motta said. "I thought they had taken Dr. J out so I told Greg to go in to play Steve Mix. Then I found out Dr. J wasn't out, so I had to bring Bobby right back in. Greg understood what had happened, so he wasn't upset."

Motta rested Hayes to start the final quarter and then, with the Bullets on top, 85-76, with 10:25 to play, brought in Johnson for Grevey, "because Kevin was tired and I had to have C.J. in the game then. I also wanted Larry to stay in because Philadelphia had Lloyd Free in and Larry has his number."

Midway through the quarter, Motta made his other substituting error. Erving went out for Philadelphia when Johnson came in for the Bullets, but Motta left Dandridge in.

Twenty seconds later, Dandridge picked up his fifth foul while guarding Steve Mix and Hayes had to replace him.

"I blew it," Motta said. "I never should have left Dandridge in when Dr. J came out, never in those circumstances."

Then with 6:50 to play and the Bullets ahead, 97-87, Motta brought back Dandridge "because it was time to go with out best and play."

Dandridge scored eight points down the stretch and Erving none and Motta was looking like a genius.

"Everytime I make a substitution it seems to work. It's a bit of genius and a lot of luck."

- Bullet coach Dick Motta