Three months ago, when Redskins were celebrating the selection of offensive tackle Mark May as their No. 1 draft choice, scout Charley Casserly was on the phone with another defensive tackle, this one a lightly regarded free agent named Joe Jacoby.

"Joe, the Redskins are an ideal situation for a young guy like you," Casserly remembers telling Jacoby, a 6-foot-7, 299-pounder from Louisville. "There is opportunity for you to come in and have a shot at making a pro team even as a free agent. I'm not giving you a line, either."

Jacoby agreed with Casserly and decided to sign with the Redskins instead of Dallas. Now, with May holding out and veteran Terry Hermeling apparently going to retire again instead of coming to camp, Jacoby suddenly finds himself the team's No. 3 tackle.

That's good news, of course, for Jacoby but it also illustrated the radical changes, especially along the offensive line, that are taking place on this club. Joe Bugel, the offensive line coach, says that's great as far as he is concerned.

"We're not like a lot of teams and coaches," he said. "We aren't afraid to go with young people.You get to a point where you have to make decisions, where you have to say, 'It's time to break with the past and go for the future.'"

Hermeling, the 11-year veteran who has been a line fixture since 1971, won't verify that he is going to retire -- "I don't have any comment," he said -- but Redskin officials heard last week that he was stepping aside and they don't expect him to report with the other veterans next Friday. Those officials said they were relieved to hear about his plans, since it eliminated the problems they were anticipating if, as expected they wound up releasing him later in camp.

Sources close to Hermeling, the last Redskin left from the 1972 Super Bowl team, indicated that he did now want to come to camp and be cut, something he knew was going to happen unless young Jerry Scanlan, who had moved ahead of him on the depth chart, was hurt or proved he wasn't capable of starting. It had been reported in May that the Redskins were figuring on Scanlan as Hermelings replacement this year, and that story rekindled Hermelin's retirement ideas.

Hermeling, who had made it known he did not want to serve as a backup, was convinced the Redskins were not treating him properly, since he was talked out of retirement in the offseason by the new staff, with the understanding he would be a starter.

"By retiring now," said on source, "this is Terry's way of one-upmanship. The Redskins wanted him around as insurance, not as a starter. He wasn't going to be used that way and now, if Scanlan gets hurt, Terry's out there, ready to have them ask him to come back. And he probably would. But I don't think they are going to do it. He wasn't in their plans, anyway; that was obvious."

Hermeling's expected departure leaves only two longtime line veterans, guard Ron Saul (33) and tackle George Starke (33). Starke is safely entrenched at right tackle. Saul will begin camp in a backup role, trying to regain his first-string position from Fred Dean (26), who has been moved over from tackle to add more youth to the guard position. If Saul can't move up, he, too, likely will be released.

With either Melvin Jones or Russ Grimm the likely starter at guard opposite Dean (and veteran Dan Peiffer the current No. 1 center), Starke becomes the only holdover starter from the line that opened last year against Dallas.

The longer May holds out, the more it enhances Jacoby's situation. He currently is competing with Allan Kennedy (6-7, 270), the 11th-round pick from Washington State, for the third-tackle role, a spot May most likely would fill if he signs. The Redskins will carry only three tackles, since Dean also can move to that position in an emergency.

A year ago, Jacoby was an out-of-shape lineman who was considered a reject by the scouting combines. Casserly wasn't impressed, either, except by Jacoby's size, which is ideal for the Redskin's blocking system. Casserly kept checking Jacoby's progress, encouraging him to life weights after his senior season.

"Joe played well last against some good competition last year," Casserly said, "but he didn't have real good upper-body strength. He just never lifted much. But he is an eager learner and he'll do anything you ask of him. He got on weights and really took off."

Bugel and Casserly worked out Jacoby a week before the draft. Bugel couldn't believe it when Jacoby, who has improved his bench press from 315 to 405 pounds since January, walked through the door and more than filled the space. The two told General Manager Bobby Beathard to sign Jacoby as a free agent.Beathard, who had not thought Jacoby was a prospect, finally agreed, giving in to Casserly's salesmanship.

"I was 275 when I came to the first minicamp at Redskin Park," Jacoby said, "and now I'm at about 300. But it's not fat. I think they were suprised at how much bigger I had gotten. They gave me a real good chance at the next minicamp and I think I caught their eye."

He has. Bugel ascknowledges that Jacoby is far from a polished player. "But he has that great size and real good feet movement and he takes instruction well," Bugel said. "He's a bit ahead of Allam right now. But if he keeps progressing, I'd keep him around. I wouldn't be afraid to use him.

"We'd like May back," said Bugel. "We knew we needed offensive tackles; that's why we drafted him. But we're fortunate we covered ourselves by signing more guys like Jacoby.

"How can you pass up a guy who is 6-7 and weighs 300 pounds? You'd be nuts not to give him a shot. Maybe with this guy, we got real, real lucky." CAPTION:

Picture 1, Redskin big men Joe Jacoby, left Melvin Jones and Russ Grimes go through paces at training camp. Jacoby is a free agent. By Richard Darcey -- The Washington Post; Picture 2, Joe Gibbs is the man in command as the Redskins shape up in Carlisle, Pa.