Running back Napoleon McCallum of the Naval Academy was the speculation pick par excellence in the National Football League draft Tuesday. Nearly every NFL personnel director knew it. McCallum has size, speed, strength -- and a five-year military commitment.

So the question wasn't if he would be drafted, but when? No one doubted the risk factor, and everyone wondered which team could afford the risk.

The Los Angeles Raiders provided the answer by selecting McCallum in the relaxed calm of the fourth round -- pick No. 108, to be exact. Moments earlier, it seems, sirens had sounded in the mind of Al Davis, the Raiders' managing general partner.

"Last year, I felt we should pass on running back Herschel Walker in the fourth round. I thought we could get him one round later," Davis said yesterday.

He was wrong. Instead, Dallas chose Walker -- who is under contract with New Jersey in the U.S. Football League through 1988 -- in the fifth round with pick No. 114.

"I vowed then that I would never let that happen again," Davis said.

McCallum, 22, was on a recruiting trip in New York yesterday and was unavailable to comment. He is Navy's all-time leading rusher and the first Midshipman to be selected in the NFL draft since the Steelers chose defensive tackle Glen Nardi in the 16th round in 1973. (Nardi served his five-year commitment and never played in the NFL.)

Other Navy players, such as New York Giants receiver Phil McConkey, fulfilled their commitments, then signed in the NFL as free agents.

"Napoleon is a good player with excellent potential to be a great player," Davis said.

The Raiders must sign McCallum in order to retain his rights once he departs the Navy. If they fail to sign the 6-foot-2, 214-pound running back by the 1987 draft, McCallum will be open to draft by another NFL team.

Should McCallum fulfill his five-year commitment -- and there is no indication that he won't -- he would be able to join the NFL at age 27. This is the age at which Roger Staubach, Navy's former Heisman Trophy-winning quarterback, began an 11-year career that included stops at four Super Bowls and a finish line at the Hall of Fame.

So now the new question is this: Might Davis, the NFL's rebel with a cause, take on the U.S. Navy and try to spring McCallum early?

"Let's just say we took him with the idea that he has a commitment. We'll live with that," Davis said.

Some have talked of the potential explosiveness of a Dallas backfield with Tony Dorsett and Walker. How about the combination of the Raiders' Marcus Allen and McCallum? Spell it T-N-T. (If McCallum does join the Raiders in five years, Allen will be 31, which is the age of the league's two oldest running backs, Dorsett and Chicago's Walter Payton.)

Charles Casserly, Redskins assistant general manager, said the Redskins would not have considered selecting McCallum until the sixth round, or lower.

Casserly said he spoke with McCallum earlier this spring and the running back told him that he planned on using about 30 days' leave each summer to practice with his prospective team, although he would not be able to participate this summer. (Former Navy running back Eddie Meyers, eligible to play in the NFL in the 1987 season, has had a similar schedule since he signed as a free agent with Atlanta.)

In another development, sources indicate that Auburn running back Bo Jackson, selected with the draft's No. 1 pick by Tampa Bay, likely will bargain for an NFL contract that is at least on par with the reported five-year, $5 million deal quarterback John Elway struck with Denver three years ago.

Jackson said he will await the major league baseball draft on June 2 before determining whether to turn professional as a center fielder or as a running back.

Meanwhile, Pittsburgh's personnel director, Dick Haley, said the fact that 57 of the 335 college players tested positive for drugs in a scouting combine test in January did not have major repercussions in the draft.

"It was a factor," Haley said, "but it did not have a major impact on who was being chosen. I'm sure most teams weeded some of those things out. . . . We did."

However, tight end Willie Smith of the University of Miami said Hurricanes Coach Jimmy Johnson leaked a confidential report to NFL scouts before the draft showing that Smith tested positive for drugs at the school before last season. Johnson denied it.

Smith, an honorable mention all-America, was chosen by Cleveland in the 10th round, after having been rated a third- to fifth-round pick by some scouts. Cleveland officials said they did not know of Smith's drug tests.

Beyond the intrigue and speculation, there was sharp emotion in this draft. The far reaches of the draft's spectrum of emotions were manned by Georgia Tech defensive back Mike Travis and Plymouth (N.H.) State running back Joe Dudek.

Travis anchored this year's draft as the 333rd and final pick, selected by San Diego. He wasn't embarrassed, just thankful.

"Better late than never," Travis said. "At least this way I have a chance."

Dudek is the former Sports Illustrated cover boy, whom the magazine championed for the Heisman Trophy last season. Dudek ran for 5,570 yards against Division III competition -- only Dorsett and Charles White ran for more on the collegiate level -- and expected to be drafted in the middle rounds.

He went to bed around midnight, several hours before the draft ended, realizing he would not get drafted. His was a dramatic fall, from cover boy to covered up.

Said he: "I had the champagne waiting and never got the chance to open it up. It hurt."