The Washington Capitals began informal practice under the team captain, Ryan Walter, yesterday at Fort Dupont. Prominent among the early arrivals and anxious to wipe out memories of the past season was left wing Paul Mulvey.

Mulvey, 6-foot-4 and 220 pounds, was probably the main individual disappointment of the 1980-81 season, as he scored only seven goals in 55 games before being sent to Hershey for the duration.

The year before, Mulvey had accounted for 15 goals and created so much havoc in front of opposing nets and in the corners that his teammates voted him the most improved Capital. Mulvey indicated yesterday that he probably thought he had refined his somewhat spotty skating and stickhandling skills, too, and was only fooling himself.

"I think the major reason I had such a bad year was that I was a little overconfident and trying to play a game that wasn't mine," Mulvey said. "I have to play a crash-bang, rough game, not a finesse, skating game. I started trying to finesse it and I got worse and worse.

"I was stubborn and (Coach) Gary (Green) got down on me and I was sitting out and I got in worse shape. I think it was better to go down and get it out of my system. When I finished in Hershey, my game was picking up. I was pounding in the corner and I was first on the puck. It wasn't totally gone."

Mulvey became engaged in the off-season and also dedicated himself to proving he can play in the National Hockey League.

"All summer Mac (Paul MacKinnon) and I worked out," Mulvey said. "I worked on weights to strengthen my upper body and I've been riding the bike, working on my legs more so than before, to get some more strength in them.

"I'm fairly confident I can change things. I hope Gary is, too."

Others in the first-day group were Finnish defenseman Timo Blomquist, Pat Ribble, Alan Hangsleben, Dennis Maruk, Tim Tookey, Errol Rausse, MacKinnon and goalie Rollie Boutin. The numbers are expected to grow daily as players voluntarily arrive to get a head start on training camp. Formal training starts in Hershey Sept. 13 and the next day a large contingent will depart for Sweden and the Dagens Nyheter Tournament.