After visiting with Broncos personnel during the NFL scouting combine in Indianapolis last week, a prominent agent got the impression that defensive tackle clearly was the team's top target. An NFL coach, meanwhile, said he thought the Broncos might draft a cornerback in the first round of the April 25-27 draft and take another cornerback in the second round. The low-volume conversations in the downtown Indy hotel lobbies last week confirmed the Broncos' positions of need. Denver and 31 other teams can start negotiating with free-agent players Saturday. The Broncos can start adding to their roster March 12. "We have a lot of holes, and we have a lot of room for improvement," coach John Fox said. Besides cornerback and defensive tackle, the Broncos also want to upgrade at running back and on the offensive line. Those four positions are Denver's priority. Adding depth at wide receiver and safety would be considered a bonus. A look at the Broncos' positions of need: Cornerback Beginning with the tragic death of Darrent Williams in the hours after the 2006 season, right cornerback has become an elusive, unsolved mystery. Not that the Broncos haven't tried — hard. Since Williams' death, the team has thrown a combined $40 million of Pat Bowlen's money at Dré Bly, André Goodman, Drayton Florence and Tracy Porter, only to receive modest to disappointing returns. Porter will enter free agency, where he must deal with seizure concerns. Third-year defensive back Chris Harris is better suited for the nickel, where he might be one of the top five in the NFL. Second-year cornerback Omar Bolden will likely get more playing time in 2013, but he probably needs one more year before he's ready to become a trusted starter. Tony Carter will return, but he might not have the size or strength to hold up over 16 games. Not only do the Broncos need a starting right cornerback, for the first time since 2004 they have to start thinking about Champ Bailey's heir apparent. The 12-time Pro Bowler will turn 35 in June and is coming off a rough playoff game against Torrey Smith and the Baltimore Ravens. Read more: Denver Broncos' offseason needs: CB, DT, RB, OL lead the way - The Denver Post Read The Denver Post's Terms of Use of its content: Follow us: @Denverpost on Twitter | Denverpost on Facebook