Not long after arriving in this big wide place to prepare for the third annual Kickoff Classic at Giants Stadium Thursday night, Coach LaVell Edwards of Brigham Young said he figured 90 percent of his team never had been to New York. Then he said he figured about half would never come back.

All those miles away from the clean air and open spaces of the Great Salt Lake Valley, it seems the only and best defense Edwards and his formidable rank of do-rights have against this world is goodness.

The other day, for example, some of the defensive toughs for Boston College were heard to wonder at the ways of Robbie Bosco, the BYU quarterback who will begin his senior season with the 8 p.m. game (WDCA-TV-20). You hear about all the love and attention Bosco gives to handicapped kids, and about how he never curses, smokes, drinks or chases women. And you wonder how anyone of right mind can want to take the fellow's head off and do a little dance on his tonsils?

Even Jack Bicknell, the Boston College coach, said recently, "They're good people, really fine."

But BYU, which makes its home in Provo, Utah, brings more than a working Mormon example to the East Coast. The Cougars won the national championship last year and have a 24-game winning streak, the longest in the nation.

In a recent telephone interview, Edwards said the Boston College game was not a "win-or-die kind of thing," but an "opportunity for us to play to a large audience and start the season off right." Then he said it was a good and proper way for Bosco, who finished third in the 1984 Heisman Trophy balloting, to once again showcase "the great courage and talent you saw against Michigan in the Holiday Bowl."

In that game, Bosco overcame a leg injury to rally his team to a 24-17 comeback victory and the national title. Although unable to plant his left foot firmly, Bosco completed 30 of 43 passes for 343 yards and two touchdowns. When it was over, Edwards said Bosco was "as good as any of the quarterbacks we've had in the past," including Gifford Nielsen, Marc Wilson, Jim McMahon and Steve Young.

Just recently, Edwards expressed regret that Doug Flutie of Boston College, winner of the 1984 Heisman Trophy, had graduated to the New Jersey Generals of the U.S. Football League and would not be around for the season opener. Last year, Bosco completed 283 of 458 passes for 3,875 yards and 33 touchdowns and finished second to Flutie in passing efficiency. "Flutie and Bosco on the same field," Edwards said, "what can you say about it? That would have been something to see."

In place of Flutie, who had started every Boston College game since Oct. 17, 1981, Bicknell will count on junior Shawn Halloran, a classic dropback passer with little playing experience. Halloran completed only three of six passes last year for 19 yards, but in 1983, he helped lead the Eagles over Rutgers, 42-22, when Flutie suffered a concussion.

Although Halloran lacks great scrambling ability, Bicknell said he "wasn't slow" and can probably throw the ball as well as any other college quarterback. He also said Halloran had the ability "to become a star in his own right."

Halloran, who has no doubt grown weary of being compared with Flutie, will face an enormous challenge against the BYU defense, which is led by linebackers Cary Whittingham, Leon White and Kurt Gouveia, and defensive backs Jeff Sprowls and Marc Sherman.

In the Holiday Bowl last year, the Cougars' defense held Michigan to minus-three yards in the fourth quarter. Duplicating that effort may prove impossible against Boston College, which returns tailback Troy Stradford, an all-America candidate who missed three games last year with a pulled hamstring but still ran for 666 yards on 146 carries.

More than anything, Bicknell said, he worries how his young defensive secondary will perform against Bosco and the BYU receivers, led by Glen Kozlowski, who has 4.5 speed.

"It's my biggest area of concern," he said, "even bigger than the quarterback situation . . . If we struggle, we struggle. But you have to believe everything will fall into place . . . I wouldn't be surprised if we were real good this year. You just can't know."

Among those Bicknell will rely on to carry the load is senior nose guard Mike Ruth, who is probably the strongest player in college football. Ruth is 6 feet 2 and 250 pounds and can bench-press more than 550 pounds. He can also cover 40 yards in 4.8 seconds.

"You don't know what kinds of team we'll be until you put us out there," Bicknell said. "And it's the same for them . . . Everybody's been practicing for what seems like a year now. I think both sides are more than ready to play."