It was going to be a glorious draft, possibly the best ever in the National Football League. Teams stockpiled 1983 choices in anticipation. General managers polished their best adjectives.

And then along came the U.S. Football League.

Not that the NFL draft Tuesday--a 12-round one-day marathon--will be a bust. But when five or six probable first-round choices signed with the new league, it took the heart, if not the soul, out of the selection process.

Instead of having so many players of first-round caliber available, there now may be a shortage of top choices to satisfy all 28 opening-round selections.

Instead of being maybe the best draft ever in terms of available running backs, it now ranks much lower.

Still, this draft remains one of the best in years, especially in depth at quarterback and cornerback. There are some excellent players waiting to be chosen so they can start bidding wars between NFL and USFL teams.

The only consolation for the NFL: it could be worse. Quarterback John Elway could have signed with the USFL, too. Or he could be wearing New York Yankee pin stripes on some minor league farm team.

Elway has saved this draft from being ordinary. Scouts almost unanimously agree that a player of Elway's ability comes along infrequently. Even those talent judges who rarely praise anyone, people like New England's Dick Steinberg and Washington's Bobby Beathard, become starry-eyed when talking about Elway.

If there is such thing as a franchise player in football, Elway is that person. He could take over as almost anyone's starting quarterback next season and, barring injury, stay a star for years. He has the poise, the physical qualities and the maturity to more than adequately handle football's most demanding position.

He's so good New England already has offered three No. 1 choices to Baltimore for the right to pick the first player. To draft Tony Dorsett No. 1, the Cowboys gave up one No. 1 and three No. 2s. To draft Earl Campbell No. 1, the Oilers gave up Jimmie Giles plus Nos. 1, 2 and 3.

By all but refusing to play in Baltimore, Elway is forcing the Colts to make a trade. If they don't, it seems unlikely Elway will sign a contract to play in Baltimore. Instead, he would opt to sign with the Yankees, who own his baseball rights. The Colts still could draft Elway and hope he'll change his mind. But that would be risky for Baltimore, which could fill a lot of needs with the choices acquired in a trade for the Stanford star.

So there should be at least one major trade prior to the 8 a.m. start of the draft, with the Colts sending their No. 1 pick to San Diego for two or three of the Chargers' first-round choices. Likely there will be more deals, as teams like Houston (third pick after switching first-round order with Los Angeles yesterday for a fourth-rounder this year and another in 1984) give up their high choices for depth in the early rounds.

It's almost useless to project which players specific teams will select. It's far easier to pinpoint the players most likely to be gobbled up early in this draft.

* Eric Dickerson, SMU, halfback. He's already rejected a $1 million-plus offer from the USFL. An accomplished runner with breakaway speed, he alternated with Washington Federals back Craig James. Yesterday's switch of Nos. 2 and 3 spots in the first round could result in his going to Los Angeles.

* Curt Warner, Penn State, halfback. Bothered by leg cramps in college, he still is a polished performer with proven toughness.

* Billy Ray Smith, Arkansas, linebacker. A defensive end in college, he will be an inside linebacker in the pros. One of those players with instincts coaches can't explain, only praise. He could become an Oiler as a result of yesterday's trade of picks.

* Mike Pitts, Alabama, defensive end. A good pass rusher, he's the top-rated defensive lineman in the draft.

* Quarterbacks Tony Eason of Illinois, Jim Kelly of Miami (Fla.), Todd Blackledge of Penn State and Dan Marino of Pittsburgh. Going into last season, you'd expect Marino to head this list, but he played poorly last year. Still, all four may go in the first round.

* Terry Kinard, Clemson, safety. The top-rated defensive back in the draft, he has stiff competition from cornerback Tim Lewis of Pittsburgh.

* Tony Hunter, tight end, Notre Dame. Tight end is one of this draft's weak areas, but Hunter should be an immediate star.

* Chris Hinton of Northwestern or Jimbo Covert of Pittsburgh will become the first offensive lineman chosen. Both are big, as is Nebraska center Dave Rimington.

According to scouts, teams in need of help at linebacker, defensive line and running back (beyond the early stars) will have problems in this draft. There isn't much depth at wide receiver, either, but offensive linemen are prevalent, along with defensive backs and quarterbacks.

The effect of the USFL is being felt on this draft in one other way. The 8 a.m. start initiates a one-day session that will continue until the final selection. That could take place some time early Wednesday morning. The NFL decided this procedure will enhance its chances of signing more choices. It likely will be a better test of what teams can stay alert the longest. CAPTION: Picture 1, Eric Dickerson has already turned down $1 million- plus from the USFL. UPI; Picture 2, Despite a poor 1982 season, Pitt's Dan Marino may go in first round. UPI; Picture 3, John Elway save the draft from mediocrity-unless he turns to baseball. Picture 4, Arkansas' Billy Ray Smith. Picture 5, Clemson's Terry Kinard. AP