While the Boston Celtics and Los Angeles Lakers are preparing for a rematch of last season's NBA championship series, there are some who wonder if the third member of the the league's elite troika, the Philadelphia 76ers, are in a state of decline.

It didn't seem that way when the 76ers beat the Washington Bullets and Milwaukee Bucks in the opening rounds of the playoffs. The four-game sweep of the Bucks, a team chosen by many to make the finals, seemed to be a sign that the Sixers had lost little despite a so-so regular season.

Yet it only took defending champion Boston five games to eliminate the 76ers and move into the finals, which begin here Monday afternoon. Wednesday night's 102-100 Celtics victory at Boston Garden exposed a number of the 76ers' weaknesses.

The 76ers are the shortest team in the NBA, a fact the Celtics exploited. Seven-foot center Robert Parish, 6-11 Kevin McHale and 6-9 Larry Bird all enjoyed an edge over their Philadelphia counterparts, Moses Malone, Charles Barkley and Julius Erving.

Age is another weakness. Erving is 35 and has played professional basketball for 14 seasons. Bobby Jones, who started for Barkley in three of the five games, has played for 11 years, as has Malone, who seemed fatigued throughout the series.

The ever-increasing strain between guard Andrew Toney and Coach Billy Cunningham also hurt the team. Toney's freewheeling offensive approach has upset Cunningham on occasion, but in this series the coach found himself needing a player to take control of the action, particularly in the face of a defense keyed to stop the 76ers' inside game. When that individual boldness wasn't forthcoming, Philadelphia's offense often sputtered.

"I think we came back well and showed that we're a very proud team," said guard Clint Richardson. "We were right there, and we'll be back up at that next level."

Boston and Los Angeles already are there and this season's final might be more exciting than the seven-game series played by the two teams a year ago. One reason is the emergence of stronger supporting casts.

While Bird is clearly the Celtics' most valuable player, the value of guards Danny Ainge and Dennis Johnson has become increasingly obvious. For Los Angeles, Byron Scott, who threw away a pass in the final seconds of Game 2 in last season's finals, has been the most prolific scorer for the Lakers this time around, hitting well over 60 percent of his shots.

Magic Johnson, blamed by many for the Lakers' failure last season, is eager to redeem himself after a series of miscues against Boston damaged his reputation as a great clutch performer.

Bird says he's ready to atone for his last nine games. Although his team won six of those games, Bird played more of a support role. He shot under 50 percent in most of those games and scored well below his regular-season norm of 28 points a game.

"I didn't shoot well this series, and I just didn't play well," Bird said after Wednesday's game. "Usually when I don't shoot well, I do other things like rebounding, but I didn't do much of that this series either. I've got to get back to my game."

Bird averaged seven rebounds per game against the 76ers, three below his regular-season average. Still, as Boston Coach K.C. Jones pointed out, "You always knew that he was in the game, though, didn't you?"

The key to this series appears to be the Celtics' ability to slow down the Lakers' fast break, which helped them score 153 points in their series finale against Denver. "I don't think we're intimidated or scared (about the L.A. break), but a little more concerned," said Boston forward Cedric Maxwell. "I'm confident about what we have to do."

The Lakers' main concern will be whether they can withstand the pounding that's sure to be a big part of the Celtics' game plan. Last season's finals turned partially on a single play in Game 4 in which the Celtics' Kevin McHale clobbered forward Kurt Rambis.

The flying tackle seemed to spur Boston, and from that point on, the team's increased aggression played a big part in wearing down the Lakers.