Midway through his third year in the National Hockey League, Peter Stastny of the Quebec Nordiques finds he still is adapting to the experience.

"I cannot say I have completely adjusted to the season, the schedule," said Stastny, whose team will face Washington tonight at Capital Centre. "In Czchoslovakia, a shorter schedule, a different system. There is nothing similar to compare."

Stastny and his younger brother Anton made hockey history when they defected from their homeland before the 1980-81 season, trading life on their Slovan Bratislava hockey club, and the Czech National team, for Nordiques jerseys. Last season, their older brother Marian joined them.

And according to Peter, their total NHL indoctrination is taking time. "It doesn't come in just one year or even two," he said. "One thing I am getting adjusted to, a little, is the long season."

In Czechoslovakia, Stastny said, the individual teams played perhaps 40 games. "Then the National team would have time (away from the other teams) just to prepare itself. The players go to camp and just work themselves into shape for April. Here, the schedule doesn't work around a team like that; it's all the individual teams that are important.

"My first year here, by January, I was very shaky. I felt kind of like in a slump, tired," he said. His brothers shared the difficulty, but, with conditioning, are growing more used to the marathon schedule and rigorous travel. "In Czechoslovakia, the travel was not the same. And the opposition was not that strong. The Swedes, the Russians--those were the good teams--but the others were just not strong and you knew you would win against them."

The Capitals' defeat of the Nordiques in Quebec earlier this month was the first look Stastny had had of the improved Washington product. He was impressed, partly because Washington shut out the brothers Stastny.

"They've got a very well-balanced team," Peter said. "Offensively, defensively, goaltending, their three or four good lines . . . they are hard to beat."

In spite of occasional language troubles, and trying to fit into a different game, Peter Stastny said he would not turn back the clock. "Why should I ever go back?" he said. "I enjoy it here."