A year ago, when he became the Redskins' second No. 1 selection in 13 years, Mark May was hailed as the team's dominant offensive tackle of the future.

Now, after a rookie season in which he lost his starting tackle spot to free agent Joe Jacoby, May is being switched to guard, a move he realizes could allow him to start next season.

"Melvin Jones (last year's starting right guard) is still having neck problems and Fred Dean has had a history of injury problems," said Joe Bugel, the offensive line coach. "This is a chance for Mark to play this season. He's too good to sit on the bench and we aren't good enough to let one of our best five linemen sit, either. We'll try him at guard in minicamp and if he progresses, we'll keep him there. I think he could turn out to be a hellacious guard."

A new position is not the only change for May. He says his attitude has changed and his appearance has, too.

A six-days-a-week offseason lifting and running routine, supplemented by four meals a day, has increased May's weight from 255 to 283. His neck and arms are two inches bigger, his chest and thighs four inches. And he is appreciably stronger than the rookie who thought he could manhandle the pros the way he manhandled college opponents.

"I used to weigh over 300 pounds but this is different," said May. "I've been lifting so much that this is muscle. I came in last season not weighing enough and I wasn't strong enough. I got worn down. Now I'm 283 pounds and stronger. It will give me an edge because I'm going to be bigger than many of the guys I'm going to block. I feel better about things already."

May's struggling first season is not unusual in the NFL. Fans may expect a player selected in the first round to become an immediate star. But especially for linemen, the learning process usually takes longer. Only 13 first-round picks in each of the last two seasons have started by the end of their rookie year. Yet, by the end of 1981, 22 of 1980's top choices were first stringers.

"You can't imagine the pressures," May said about being a No. 1 selection. "I never thought it would be like it was. You are watched, everything you say is watched, your every move is reported. You can't mess up. You feel you have to be good right away, that you have no time to develop.

"As a rookie, things are different. You wonder where you are going to live in Washington and how you are going to move all your stuff there, things like that. In college, you were taken care of, your room was provided, your meals were provided. Suddenly, at age 21 or whatever, you are on your own. Sure, that's part of growing up, but that doesn't make it any easier."

May also had some unique problems. He was a holdout, missing the team's final minicamp and the first week of training camp. While his peers were learning plays and perfecting techniques, May was in Pittsburgh, fishing and trying to stay in shape by playing racquetball. When he finally reported, he almost immediately was made the starting left tackle after playing only the right side in college and high school.

"No question the holdout hurt him," said General Manager Bobby Beathard. "He never caught up," said Bugel. "Everything was rush, rush, rush."

Says May, who wound up signing a four-year, $650,000 contract: "From a personal standpoint, I'd do it again. I had to live with myself, I had to sign for what I thought I was worth. From a playing standpoint, there is no question it hurt me. When I came in, I could see I was behind. I began pressing, trying to catch up. I never felt comfortable.

"As far as playing the left side goes, I tried. It wasn't easy, it wasn't comfortable, but I did the best I could. I wouldn't mind playing on the right from now on, however."

May, a friendly, outgoing man who remained remarkably candid during his rookie ordeal, admits he also made a major error. "I let my weight drop from the 280s to 255. I should never have done that. My college coach was telling me to stay at 280, but some scouts were saying that was too heavy, that I should be 260 or less. I listened to the wrong voices."

May compounded his troubles by not working out in the weight room. He was usually the first Redskin dressed and into his car after practices. "In college, I could maul people around. Here, I should have been trying to maintain my strength to stay competitive," he said. "I didn't and it hurt me. Now I'm going to do all the extras."

By midseason, his body sapped, May's performance declined. Bugel made the decision to replace his team's No. 1 choice--and his personal recommendation to Beathard. Soon afterward, May made a commitment to himself to remain here during the offseason and change his habits.

"This is a really boring way to live, doing nothing but working out six days a week," he said. "There isn't a whole lot to look forward to. But it was either do this or never get better. At first, when there weren't many other guys around, I wondered what I was doing here. But I'm not used to sitting on the bench, and I don't want to be a spectator again. So I stayed off the social circuit and kept lifting."

Says Bugel: "His attitude always has been great but now his priorities are all straightened out. He's like a college kid again, hanging around the football office. It's amazing how he's improved his strength and how he's grown. This is a 12-month job and to keep up you have to keep working out. Now he knows that.

"We aren't trying to make a position for him, no way. If we had to do it again, we'd take him. But with George (Starke) and Joe Jacoby at tackle, moving him to guard is a way to utilize his ability. We are starting over with him, right from scratch, even teaching him how to run. With him at 285 and Russ Grimm at 275 and Jacoby at 295, we're going to be a monster line. Mark is going to benefit at guard by having a guy on either side of him to help him block.

"I told Mark we are in this together. We'll work together and we'll win together. And now he knows what this league is like. Mark my words, he's going to be a really good one, a guy who's going to play 10 years of solid football."