It is not easy to physically move mountains. It is harder yet to move them emotionally.

The Washington Redskins made the latter attempt anyway, right before that crucial game in Dallas, in Week 15 last December.

That's when they enhanced the incentive clauses in the contract of defensive tackle Dave Butz, a human Everest at 6 feet 7, 295 pounds. Included was a bonus for quarterback sacks.

Butz responded with what he properly terms "the game that put it on the map." Sixty minutes of determination and rage earned Butz 2 1/2 quarterback sacks; he stopped three other running plays for losses. Butz once even chased Dallas running back Tony Dorsett, a Cowboy with giddyup, catching him from behind on a screen pass.

Butz finished with 9 1/2 tackles in the game and Dorsett finished with this pained requiem: "Butz was all over me."

The Redskins finished with a 31-10 victory in Texas Stadium and, one week later, they finished as division champions.

By season's end, Butz finished as an all-pro for the first time in his 11 pro seasons.

And what of the incentive increases? "They had not a bit to do with it," Butz said of his effort against Dallas. He said the contract negotiations had been going on for a lengthy time. General Manager Bobby Beathard said today, "Dave's performance bonuses were old. We just had to bring him up to date with a couple of other players."

And Butz, 34, who is equal parts serious and sensitive, added, "People wonder why I have better games than others. But everybody does, right?

"People wonder why I had such a great game against Dallas. God, I didn't get blocked. (Defensive end) Todd Liebenstein took the (offensive) guard and tackle and I just went after the quarterback."

Ever since Butz signed with the Redskins as a free agent back in 1975, team officials have wondered what makes him tick. He is solid against the pass, nearly impregnable against the run. Redskins officials always knew he could play as he did against Dallas. They just wanted it to happen more often.

Butz has heard this all before. "There's nothing I can do about it," he said of the talk. Then, the intimidator within him breathed fire. He added, ". . . . just deck the first guy that says it to me, I guess."

"Dave had some great games last year, particularly the Dallas game. That was one of the best games I've ever seen a defensive lineman play," said Coach Joe Gibbs. "Dave's a guy who when he goes after it, you just don't run over there . . . He can really play when he wants to."

What makes him tick? "I know I was kidding Dave in the locker room before that Dallas game," said Darryl Grant, starting defensive right tackle. "I told him, 'Today is the last day for Pro Bowl balloting.' It was, too. We had to turn in the ballots during the following week. Dave looked over and just grinned."

The selection to the Pro Bowl meant a great deal to Butz, so great in fact, that he played the game in Honolulu despite having the flu.

Butz proceeded to get two of the National Conference's Pro Bowl-record eight quarterback sacks in the NFC's 45-3 victory. "That game was important enough where I would have crawled there to play," Butz said afterward.

What makes him tick? "Dave is one of the best defensive tackles in the league," said Richie Petitbon, coach of defense. "I think when he was here the first time (mid-70s), he was the outsider coming in. The older guys on that team were cliquish. Dave wasn't a part of the clique. He was an outsider."

Petitbon said that changed when the line coach, Lavern (Torgy) Torgeson, returned, with Gibbs, in 1981. "For the last two years," Petitbon said, "Dave's played well."

Once, it was said that Butz was not an accomplished pass-rusher, that his primary salary-earning talent was run defense. Before last year, he never had recorded more than six sacks in a season.

Now that theory is treated as so much balderdash. "They can't say anymore that Dave can't rush the passer, not after last year," said Petitbon. Butz said, "I led (the team) in sacks last year with 11 1/2. And how many (offensive) people were pushing on me or how many times did I take two of them and somebody else (on defense) was left open?"

Butz remains an enigma in the locker room. "He kids around a lot, but sometimes it's hard to tell," Grant said. "I try to stay clear of him when I'm not sure what his mood is."

And Butz remains in the game on all downs these days. This is something he craves because, quite frankly, that's the way his idol, former Chicago Bears middle linebacker Dick Butkus, always did it.

It was with a stonefaced glare that Butz declared his goal for this season: "Be better," he said.

He wouldn't elaborate, either.