Coach Hayden Fox can call the plays on the football field, but when he's dealing with a college-age daughter in an era of social change he's not even sure who's carrying the ball.

Craig T. Nelson, the man who plays Fox on the ABC sitcom "Coach" (Wednesdays at 8 p.m. on Ch. 4), is a considerably more complicated fellow, but he knows what his character is going through. He has kids himself."He's an anachronism," Nelson said of Hayden in an interview. "He doesn't fit in the time he's living in. I'm not sure if he was born too early or born too late, but he just doesn't understand. So he becomes the biggest liar in the world and tells everybody what they want to hear, and he's always getting caught at it."

One of the major things he does not understand is his 18-year-old daughter, Kelly, whom he hadn't seen in 16 years - until she turns up as a freshman at the college where he coaches.

"She has all sorts of ideas he's never heard of," Nelson said. "There's a boyfriend he doesn't understand at all. She has all kinds of new-fangled ideas like working for a living. Meantime he's been isolated in the traditional male world of coaching for so long."

One reason Nelson can understand Fox so well is his own family - a son, 19, a recently married daughter, 21 - "I'm thankful she knew his first name" - and a 13-year-old son.

"I'm watching a lot of this happening in my own life," he said. "It's wonderful and at the same time frightening. Things are so much quicker now, so much more accelerated than they used to be.

"I remember my dad telling me that he had lived through the horse-and-carriage era right up to men landing on the moon. That all happened in 50 years, which is an incredible perspective.

"There are all kinds of traps and decisions we never had to worry about before - why the diseases alone . . ." his voice trailed off. "I don't want to be negative, but it's scary."

He can understand Coach's problems with his make-believe daughter because his own experience with a teenage girl is fresh in his mind.

"I lived five lifetimes in her teen years," he said with a sigh.

The sitcom "Coach" character may seem a 180-degree about-face for fans who remember Nelson as Air Force Col. Raynor Sarnac on the ABC series, "Call to Glory," but that's not the way it was.

"I started out in comedy," Nelson said. He did a stand-up comedy act for about four years and also wrote comedy with Barry Levinson and Rudy DeLuca for such television stars as Tim Conway and Alan King. Levinson and DeLuca went on to win Emmys writing for "The Carol Burnett Show."

In 1973 he left Los Angeles for the mountains of northern California, where he lived for five years.

"I was dissatisfied," he said. "I was doing so much comedy, and I couldn't make a living at it. I wanted to get out."

So he built a log cabin on 40 acres, where he and his family grew their own food and raised their own animals.

"I finally went broke," he said. "When it became a matter of food stamps and welfare, I hitchhiked back to Los Angeles to see what work I could get.

"The decision to get away was because I wanted to become well rounded and show some versatility."

The experience led to his producing a series of 52 documentaries delving into the reasons why America's artists move to rural areas. The programs were syndicated under the title, "America Still."

Nelson has ambivalent feelings about doing comedy.