ENGLEWOOD, Colo. -- Since Denver Broncos owner Pat Bowlen hired him in 2011 to run the football side of the organization, John Elway has said he hopes to stick to what he believes is a proven formula for success over the long haul: to stack draft classes and make free agency mostly an exercise when the team re-signs its players.

For that to work, however, the draft classes have to replace the players the Broncos allow to leave in the open market.

That was not the plan a year ago, as last March’s free-agency binge brought in Emmanuel Sanders, DeMarcus Ware, T.J. Ward and Aqib Talib. All four players ended up in the Pro Bowl, so it was a successful endeavor. But it can’t be the way the Broncos live over the long haul, and this year’s more measured approach in free agency’s early going is proof that Elway wants the team to try to live the draft-and-re-sign life.

In Sylvester Williams, the Broncos appear to have a keeper from their 2013 draft class. AP Photo/Joe Mahoney

But the Broncos have let quite a few of their own players move on over the past two years. Last year Zane Beadles signed in Jacksonville, Eric Decker with the New York Jets, Wesley Woodyard in Tennessee, Robert Ayers with the New York Giants and Knowshon Moreno in Miami.

All of those players were former Broncos draft picks or, in Woodyard’s case, had made the team as an undrafted rookie.

This year Julius Thomas and Orlando Franklin, both from Elway’s first draft class in 2011, have signed in Jacksonville and San Diego, respectively. Also from that draft class, safety Rahim Moore and linebacker Nate Irving are expected to get their best offers elsewhere in the coming days.

For this discussion, we'll count players signed as undrafted rookies as part of a team’s draft class. If Moore and Irving do sign with other teams, that would be nine Broncos draft picks who have not been re-signed.

The Broncos re-signed cornerback Chris Harris Jr. in December, long-snapper Aaron Brewer this past week and linebacker Steven Johnson on Tuesday. But it all still puts the developmental heat on their 2012 and 2013 draft classes if the Broncos are to avoid having to wade too deeply into future free-agency markets.

From the Broncos’ 2012 draft class, Derek Wolfe, Malik Jackson and Danny Trevathan project as starters on defense, and Omar Bolden figures to play at least some on defense in addition to being the team’s kickoff returner. Quarterback Brock Osweiler will back up Peyton Manning. And, coach Gary Kubiak has said the Broncos have to find a way to give Osweiler some work.

And if Ronnie Hillman could even out his on-again, off-again performance, it would help the Broncos maintain their developmental path.

But for the Broncos to stick to the draft-centered approach, especially in the near future, the 2013 draft class will have to pick up the pace. Two players from the seven-player class are already gone -- Tavarres King and Vinston Painter.

And thus far, only defensive tackle Sylvester Williams projects as a starter. Kayvon Webster is expected to play in the dime (six defensive backs) package, and Montee Ball will enter offseason workouts as the No. 2 running back behind C.J. Anderson.

"He needs to come in like he’s the starter," Kubiak said at the NFL combine of Anderson, who made the team as an undrafted rookie in 2013.

From the 2014 class, the Broncos considered Bradley Roby a starter this past season -- he played 75.1 percent of the defensive snaps -- and the team is poised to give wide receiver Cody Latimer far more playing time. Also, Michael Schofield will be given a chance at the starting right tackle spot when offseason work begins.

In the end, the Broncos were the league’s big players in free agency a year ago, an approach they are not taking this year. And Tuesday they re-signed Virgil Green, a seventh-round pick in ’11, and added tight end Owen Daniels to the roster, but they largely left the headlines to other people.

Their ability to do that next year and beyond will be traced back to how much more they can get from their past two draft classes to go with the one that's on the way.