Mike Shanahan has done his homework. According to research by the Denver Broncos coach, 12 of the last 15 Super Bowl winners finished in the top five in the league that season in fewest points allowed; none of the 15 finished lower than eighth in that category. Last season's champs, the New England Patriots, gave up the fewest points in the NFL.

That's why the Broncos, who haven't won a playoff game in five seasons since their back-to-back Super Bowl triumphs, spent the offseason bolstering their defense. And that's why Shanahan didn't object to the suggestion made here Tuesday as his club reported to training camp, that his team has more question marks on offense than defense for perhaps the first time in his 10 seasons as Denver's coach.

"If you take a look over the last 15 years and look at all the Super Bowl champs, the one thing that's common among them is how many points the team gives up in a year," he said. "If you don't have a defense that ranks in the top five in points given up, you don't win the Super Bowl. That's the bottom line."

The Broncos spent the offseason adding veterans on defense. They bolstered their secondary by trading two-time 1,500-yard rusher Clinton Portis to the Washington Redskins for four-time Pro Bowl cornerback Champ Bailey. They signed five-time Pro Bowl safety John Lynch after he was released by the Tampa Bay Buccaneers. They added experience to their defensive line by signing veteran free agents like ends Raylee Johnson and Marco Coleman and tackle Luther Elliss. They moved up in the first-round draft order by trading cornerback Deltha O'Neal (whom Shanahan wanted to move to wide receiver) to Cincinnati, and used the 17th overall choice on University of Miami linebacker D.J. Williams, who is so athletic that John Madden once said Williams was the only player he ever had seen who could have gone straight from high school to the NFL.

The Broncos ranked ninth in the league last season in points allowed and have suffered some key losses -- especially at linebacker, where Ian Gold departed as a free agent and John Mobley was released Tuesday after failing a physical. Doctors have advised Mobley to sit out this season because of a bruised spinal cord suffered during a game at Baltimore last October.

But Shanahan faces bigger issues on offense replacing Portis and tight end Shannon Sharpe, who retired to join the CBS pregame studio show.

"Any time you lose a guy like Shannon Sharpe, there are questions," Shanahan said. "He's been very productive for us over the last couple years. But when Shannon left a few years ago and went to Baltimore, we had a few of our tight ends step up and do a good job. I expect the tight ends to do that this year. There are some unproven guys. I think we have the people to be very good. But until you get it done, there are going to be those question marks. You lose a guy like Clinton Portis who averaged over five yards a carry -- you're talking about guys who haven't proven themselves yet. There are always question marks, but I feel very good about where we're at offensively. I think we'll be very good. . . . I think we have running backs who will fit into the system and do very well."

Shanahan likely will choose a starting tailback from among second-year pro Quentin Griffin, rookie Tatum Bell and veteran Garrison Hearst. His options at tight end include holdover Patrick Hape and newcomers Byron Chamberlain, Jed Weaver and O.J. Santiago. Those four totaled 47 receptions last season (35 by Weaver for San Francisco); Sharpe had 62. Chamberlain was a member of the Broncos' two Super Bowl-winning teams before leaving and becoming a Pro Bowl player in Minnesota. He struggled with his weight, though, and served a four-game suspension for testing positive for ephedra, then suffered through a wasted season last year in Washington.

"I've always liked Byron Chamberlain," Shanahan said. "I've always liked the way he's played. He's a very smart individual. He was always a gamer. He could make a big play at the right time. The problem that Byron always had was controlling his weight. In Washington, I heard he went up to 285 pounds. That was just too heavy for Byron. When we brought him in, he weighed 250. I told him I'd love to have him if he could keep his weight under 250. If not, I don't really think he could help our football team. He guaranteed me that he would keep his weight under 250 and do the things necessary to be a great player, and he's done that. I'm excited about him being here. He's in shape to compete.

"We've got a lot of guys at the tight end position. We don't really know right now who's going to step up and be the guy. There's a lot of competition, and that's what you want to have."

The Broncos need a big season from quarterback Jake Plummer and are counting on speedy third-year wide receiver Ashley Lelie, a first-round draft selection in 2002, to become a consistent producer opposite veteran Rod Smith now that Ed McCaffey has retired.

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Broncos leftovers:

*Shanahan left open the possibility of Mobley, 30, returning to the Broncos next season if he's cleared by doctors.

"We're going to wait for John and just see if he keeps on working and gets his neck checked out," Shanahan said. "If in six months or a year he feels like he's ready to go, we'll assess it then. But right now, he's failed his physical and only time will tell. . . . It does not mean we do not want John Mobley on our football team."

*Danny Kanell enters training camp as the favorite to be Plummer's backup. The former New York Giants starter signed with Denver last September after injuries to Plummer and Steve Beuerlein. He had been out of the NFL for two seasons, playing a season in the Arena League and even trying minor-league baseball in the independent Atlantic League. The Broncos went 9-2 last season with Plummer as their starter and 1-4 with his replacements starting.

"I feel very good with Danny coming in here right now with a full offseason," Shanahan said. "Last year, he didn't have a full offseason. . . . You're always disappointed when your backup quarterbacks didn't produce and didn't come away with wins. But I thought we did some good things and gave ourselves chances to win those games. . . . I've got confidence in him."

*The Broncos hope Lynch can be a full-time player after undergoing surgery in January for the removal of bone spurs from his neck that plagued him last season.

"The question is whether he can come back and take the pounding over a year or two years," Shanahan said. "I don't think we'll know that until he actually starts hitting, but the doctors feel very good about it. . . . They looked at John Lynch and said, 'Full speed. He looks great.' "

*Shanahan said he liked everything he saw from Bailey in offseason workouts, adding: "The guy is a natural leader, a natural worker, even better than I thought he was. That's putting a lot of pressure on him. But I've been thoroughly impressed with the way he's handled himself, the way he's worked."

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Quarterback Eli Manning, the top overall pick in the draft, is waiting in Manhattan as agent Tom Condon tries to negotiate with Giants General Manager Ernie Accorsi. The Giants report to camp in Albany, N.Y., on Thursday and practice Friday. . . .

The Oakland Raiders and agent Rick Smith reached an agreement in principle with tackle Robert Gallery, the second overall selection in the draft. Smith said by telephone this afternoon that the terms of the deal tentatively were in place and the two sides were working out the language, with hopes of making the agreement official later today. . . .

Williams agreed to a six-year deal with Denver that includes about $6 million in total bonus money. Shanahan said he is hopeful that the Broncos will sign Bell, a second-round pick, by today's practices. . . . Guard Shawn Andrews, the 16th overall choice, agreed to a six-year contract with Philadelphia. . . . Wide receiver Michael Jenkins, the 29th overall pick, agreed to a six-year deal with Atlanta that includes about $3.6 million in total bonus money. . . .

Cleveland Browns officials are scheduled to meet today with agents Carl and Kevin Poston as they try to negotiate a deal for tight end Kellen Winslow, the sixth overall selection. The Browns are scheduled to report to camp Friday. Some teams shied from drafting Winslow because of wariness about dealing with the tough-negotiating Poston brothers. There is a theory among other agents that the Postons will make sure to get their clients to camp on time this year to counteract the criticism they've received this offseason. So far, though, none of their first-round picks -- Winslow, Jacksonville wide receiver Reggie Williams and Carolina cornerback Chris Gamble -- has signed. . . .

Redskins officials were delighted with their dealings with agent Jeff Moorad in wrapping up a deal Tuesday for safety Sean Taylor, the fifth overall choice. Negotiations moved quickly after Taylor finally picked Eugene Mato and Moorad to represent him, and Moorad showed up unannounced at Redskins Park on Monday to finish the agreement after Redskins officials traveled to his California offices over the weekend. It could be a breakthrough for Moorad in representing NFL clients. He is a former partner of Leigh Steinberg who handled the firm's baseball clients and became very prominent in that sport while Steinberg did the football work.

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The Detroit Lions signed veteran guard Solomon Page to a one-year contract. . . .

Pro wrestling headliner Brock Lesnar got his wish when the Vikings signed him to a one-year, $230,000 contract. Lesnar, who left a multimillion-dollar income with Vince McMahon's WWE to try to make an NFL team's roster as a defensive end, is a former NCAA wrestling champion for the University of Minnesota and lives in Independence, Minn. Agent Ed Hitchcock said that Lesnar told him to focus on trying to get the Vikings to sign him, and the team did so after watching a second workout by Lesnar on Tuesday morning. . . .

The Vikings also signed guard Tam Hopkins, formerly of the Giants, as a free agent. . . . The Giants claimed defensive end Willie Blade -- cut by Dallas -- off waivers. . . . New England signed free agent tight end Zeron Flemister, formerly of the Redskins. . . . Eagles defensive end Jerome McDougle underwent shoulder surgery and is slated to miss about the first week of training camp. . . .

Sources around the league are uncertain whether safety Rod Woodson, 39, will be able to continue his career. The 11-time Pro Bowl selection has expressed a desire to keep playing but failed a physical because of a chronic knee problem and was released Tuesday by the Raiders. . . . Two more first-round selections -- Chicago defensive tackle Tommie Harris and Detriot tailback Kevin Jones -- reached contract agreements today.