Mike Curtis stands there in the middle of the field, crouching slightly, eyes darting this way and that, a scowl etched on a craggy face in need of a shave. Some quarterbacks quiver when they look across the line at him.

Ever since he arrived in training camp 10 days ago to begin his second season as a Redskin. Curtis has been popping and hopping, bumping and thumping, bashing and crashing into people on a regular basis.

"Don't he know we're on the same team?" one young running back asked after catching a Curtis forearm in the chest.

He has been called Mad Dog, and with good reason. He is a vicious hitter on the field - in practice and in games. in a game against the Colts last year, an official made the mistake of throwing his penalty flag in Curtis' face. Mike Curtis sat up and threw it right back at him.

In short, he is the sort of football player most coaches covet, and Jack Pardee is no exception. He has moved Curtis from the outside into the middle and made him a vital ingredient in the three-lineman, four-linebacker "34" defense the Redskins will use often this season.

Curtis is delighted with the switch. Even though he started 11 games in 1977 on the outside in place of injured Chris Hanburger, he says now he was never really comfortable in the position. "Play action fooled me a lot last year," he said. "I've got a little more freedom in the middle, it's more exciting.

The 34 is a tough defense for an offensive line to block. We'll have a lot of combinations and stunts, and it's difficult for a standard offensive blocking system to adjust to. As a result, I can flow better and I should be able to get involved in more plays."

The Redskins probably will use the 34, primarily a defense against the run, frequently on first and second down. "We could use it in passing situations, too," Curtis said, "just to confuse things a little more. I think I'll be in there quite a bit."

Whether he can beat out Harold McLinton for middle linebacker in the standard 4-3 defense remains to be seen McLintor is still running with the first unit, and Pardee says no decision will be made for several weeks.

No matter what happens, Curtis will be prepared. At 35, he is the strongest man on the team, and probably in the best shape. And he still approaches a football game as if his life depended on it.

"I feel like I really have to get intense about it," he said. "I can't relax or get comfortable, I've got to use everything I have to get through it. You only have to get that emotional one day a week. Cripes, if you can't do that you shouldn't be here.

"On the day of a game, I like to be alone. I don't like to be distracted by nonfootball things. I don't like any messing around.

"On the field, I guess you could say I'm an excitable player. I try to get excitable because it makes me perform better. I never take beans (amphetamines): they're no damned good. I just naturally get myself up for this because I know what's required.

"But I never lose control in a game. Never. Now it may appear that way. But I never really do. You can't afford to. It's a good way to get hurt. You can't think right, you can't do anything."

Curtis did get rather upset a year ago in Seattle, when conditions on the expansion Seahawks - for him at least - because "intolerable." For the first time in his career, Curtis asked to be traded.

"Sometimes when I'm playing, I react to situations by going outside the parameters set by the defense," he said. "In Seattle, they were in a controlled environment where they wanted you to go exactly by the book.

"I starting complaining about some of the things they made you do. They just gave you no leeway. It was so confining. So I got out."

Seattle placed him on waives and Curtis went unclaimed, probably because no one wanted to pay his six-figure salary. The Redskins signed him as a free agent and immediately put him to work.

During the offseason, Curtis signed a two-year contract with an option year tagged on and he says now, "Physically, I could probably play four more years, if I want to."