In their last two games the Washington Capitals have thrashed two of the NHL's revered original six, the New York Rangers and Toronto Maple Leafs. A third crumbling member of that onetime elite, the Detroit Red Wings, visits Capital Centre tonight at 7:30.

The last time the Red Wings beat anybody was on Feb. 24, when they slipped past Pittsburgh, 3-2. The last time they defeated the Capitals was March 24, 1976, and since that date Washington has collected three victories and three ties against Detroit.

The Red Wings have scored one goal in the last 14 periods while extending their winless streak to 15 games. They have managed 176 goals overall, fewest by far in the NHL, and are doomed to playoff nonparticipation for the seventh straight season.

Not only are the Red Wings failing on the ice, they are experiencing disaster at the box office. Although they claim to be averaging more than 9,000 fans, body counts on Washington's three visits have indicated they may be tallying legs instead of poeple.

"There are about 4,000 people here, which is about what they had last time, when they announced 8,000," Boston announcer Bob Wilson said on the Bruins' visit to Olympia last week. Then, when the official count was given as 8,117, he added, "Well, I see the 117, but where are the 8,000?"

The Red Wings will find an unaccustomed horde in attendance tonight. The Capitals are averaging 10,816 and expect to top 11,000 after the final two games, tonight and Sunday, when Montreal drops the curtain on the local season.

The Capitals are assured at least a 500 record at home, since the success against Toronto left them at 16-14-8. They have already clinched the season's series against Detroit, giving them fice such successes. St. Louis Pittsburgh, Colorado and Pittsburgh were other victims.

One Capital who will miss tonight's contest is Bill Riley. The rookie right wing drew an automatic one-game suspension for his third ejection of the season Sunday, when he was bounced for pulling the hair of Toronto's Brian Glennie. The incident also resulted in a $1,000 fine on the Capitals.