The late afternoon sun beamed down on an unusual scene at Capital Centre Sunday. It amounted to a changing of the guard, with Wes Unseld leaning on a car in the parking lot, signing autographs for a circle of youngsters, while 100 feet away, near the press gate, Ryan Walter performed the same chore.

Unseld was on his way inside, to a final tribute from the fans he had entertained for 13 seasons as a Bullet, but there was time as always to make a few youngsters happy.

Walter was leaving, after experiencing the bitterness of a 5-4 loss to the New York Islanders that severely damaged the Capitals' playoff hopes. But he was able to hide his disappointment and chat with some of the club's faithful fans.

Like Unseld, Walter knows who pays the salary. At 23, he displays the maturity of a much older man and he is aware of what goes on in the community. Sunday, for example, he would be returning after a brief meal to present Unseld at halftime with a check from the Capitals for Unseld's charities.

The Bullets, with Unseld serving as the catalyst, have been Washington's winter sports kings for years, with that NBA championship the crowning achievement. But they are slipping now, missing the playoffs for the first time in Unseld's career, and attendance has fallen off dramatically, with only 12,755 turning out for the tribute to Unseld that marked the season's end.

Walter and the Capitals earlier in the day had skated before a sellout crowd of 18,130, boosting their highest-ever season attendance to 459,482 with one game left. A sellout for Sunday's finale, as expected, would put the Capitals 40,000 over their best previous figure in 1976-77.

It is apparent that the Capitals are capable of a big breakthrough, if they can show enough improvement by next fall to compete effectively with the Patrick Division teams they will be facing eight times each -- the Islanders, Rangers, Philadelphia and Pittsburgh.

That breakthrough almost occurred this past winter, as the team held 10th place for much of the season. Injuries, particularly to the goaltenders, derailed the Capitals' playoff express, however, and the club never has been able to get back on the track, despite occasional outstanding efforts like last week's 5-2 victory in Philadelphia.

The Capitals, one point behind Toronto in the fight for the final playoff spot, no longer control their own destiny in the chase. They need help from either Chicago or Quebec, the two teams Toronto will face this week, as well as a big effort themselves. The schedule is not favorable.

Washington visits Boston Thursday and the Islanders Saturday before returning for Sunday's finale against Detroit. Never in seven years have the Capitals won a game in either Boston Garden or Nassau Coliseum. Meanwhile, Toronto has home games against Chicago and Quebec before visiting the Nordiques on Sunday.

If they should fall short, however, the Capitals probably will not be facing the wrath of their fans, a backlash that reached a peak two weeks ago with that 6-4 home-ice loss to Quebec. The recent revival, the ties with St. Louis and Montreal and the win in Philadelphia, have renewed hopes for next year.

Besides the solid nucleus of Mike Gartner, Dennis Maruk, Walter, Bengt Gustafsson, Rick Green and Paul MacKinnon, there will be a payoff from the ample ice time doled out this season to Howard Walker, Jim McTaggart and Darren Veitch. That defensive trio has made mistakes, occasionally costly ones, but the improvement has been remarkable.

"We have three rookie defensemen in there, that's evident," said Coach Gary Green. "Maybe after a loss, you're tempted to question the inexperience, but last week after three wins the young legs with their quickness and strength looked pretty good.

"If you can go with young guys, it's great experience for the future. Experience in pressure situations is invaluable. Veitch, McTaggart and Walker are our defense of the future. We have confidence in them and it's great to be able to put their backs up against the wall and see how they perform for you."