Joe Restic, Harvard's rookie football coach, unveils a new look offense and a shifting, stunting defense Saturday when the Crimson opens its 1971 season against Holy Cross at 1:30 p.m. in Harvard Stadium.

As usual, the opener should serve more as a polishing opportunity than as a real test of the stuff of which the 1971 Harvard squad is made. Holy Cross, the team Harvard edged 13-0 two years ago (a week before the Crusaders were stricken with an epidemic of hepatitis), had a resounding 0-10-1 record last season.

But Restic is cautious about his debut. "Holy Cross doesn't have much depth," he said yesterday. "But their two starting teams are experienced and they have a lot of fight."

Doubtless the Crusaders will be aiming for an upset win over a Harvard team that returns 13 starters, from last year's 7-2 Ivy League runners-up. Last Saturday, the Crimson dropped a 24-23 game condition scrimmage to the University of New Hampshire, but Harvard is still a heavy favorite over Holy Cross.

The Crusaders also have a new coach this season, Ed Doherty, but the problems they faced in digesting Doherty's new system could not have been as legion as those encountered by Restic's proteges. The squad arrived in Cambridge on September 2 and began two-a-day workouts the next morning. They changed back to one practice a day Monday, but only after they had smoothed out Restic's complex of formations, motion and play action.

The guts of Restic's system lie in outguessing the opposition and disrupting its normal patterns both on offense and defense. His personal forte is his imagination, which, coupled with a willingness to try just about anything once, will give Harvard a multitude of offensive and defensive variations on which to draw.

At the same time, Restic realizes the necessity of tempering daring with equal doses of moderation and caution. His cautiousness is founded primarily in planning, in making allowances for each gamble he takes. When asked early in the preseason about his strategy, Restic said, "We want to play an exciting game, but if it's a question of being exciting versus winning, the exciting part goes. We want to win, and we want to win right away."

The Crimson will show only about a third of its offensive sets this weekend, due mainly to the fact that it takes time to iron out all the cogs in a system as varied as Restic's.

Eventually, Harvard quarterbacks will be able to go with tight "T", spread, single wing, "I", slot and double slot formations. Also, they can fall back on myriad forms of motion in the backfield to influence the opposing defense.

The Crimson defense will have a similar range of choice in choosing sets to break up opponents' offensive continuity. Restic uses both odd and even man fronts, stacking linebackers and backs in odd positions, and he rolls the defense to adjust to pre-determined weak spots. The downmen and linebackers are distinct from the deep backs in that they call separate sets on each down; but the two defensive calls are coordinated.

"We know is advance where the weak spot is on any given defensive formation," Restic says. "So when the other team begins to go to that spot, we can adjust immediately and they have to begin probing for the new weak point."

"You see, our success depends on making it impossible for the opposition to know what we are going to do from week to week, and even from one series to the next. Both on offense and defense, our game is styled to confuse the other defense or quarterback; that way we have the advantage because we hopefully will know what we are doing."

After three weeks with the team, Restic is pleased with the progress the Crimson has made. Yesterday, he said he was encouraged by the team's ability to "assimilate" the new system. That means the team should know what it's doing come Saturday, and that could spell trouble for Holy Cross. Last spring, Restic said the only possible limitation he could foresee for this season was a mental one, and apparently he feels that this obstacle is no longer a factor.

Restic is confident that his quarterbacking corps--Rod Foster, Eric Crone, Frank Guerra and Jim Stoeckel--understands the flexibility and capability of the new offense, and, not surprisingly, he thinks the defense is coming along even faster, with Spencer Dreischarf and captain David Ignacio calling the signals.

While a scrimmage loss to UNH is nothing to brag about, no one connected with the football program seems overly concerned with the outcome.