Proportionally, the Broncos' tight end position faces more uncertainty than any other position group this year -- or perhaps any year -- as free agency begins.

One hundred percent of Denver's 2014 production at tight end is scheduled to hit the market March 10, with Julius Thomas, Jacob Tamme and Virgil Green all due to become unrestricted free agents.

Executive Vice President/General Manager John Elway noted that he attempted to craft a contract to retain Julius Thomas last year but failed to work out a deal.

"They wanted to test the market," Elway said on Feb. 19 at the National Scouting Combine.

Given the Broncos' needs at other positions -- specifically the offensive line -- and the $12.82 million committed to Demaryius Thomas by placing the franchise tag on him, keeping all three tight ends appears unlikely.

But it would still be no surprise if they retained multiple tight ends whether possibilities re-open with Julius Thomas, or through the retention of Green, Tamme or both. Tamme told Sirius XM NFL Radio on Feb. 16 that he would "love the chance to be back in Denver," and if Peyton Manning returns for a fourth Broncos season, Tamme would be a logical piece to retain, given his timing with Manning and his growth into a special-teams leader.

Green is an interesting case, because he could attract interest as an under-the-radar target for other teams, especially after playing extensively late last season as Thomas grappled with a sprained ankle that sidelined him for three games and hindered him in three others.

In large part due to his ability as a run blocker, Green actually graded out higher in ProFootballFocus.com's ratings than Thomas in 2014 -- plus-5.7 to Thomas' plus-5.4.

Green's opportunities as a target were limited, but his two receptions from Brock Osweiler -- including the first touchdown of their careers -- in the regular-season finale offered a glimpse of untapped potential.

"He's kind of our rock, because he was asked to do a lot of different things," Elway said. "he played 'Y,' he played 'F,' and he's also played a little bit of fullback. He does it all. Very versatile.

"We like Virgil a lot, too. We'd love to have him back."

And if the Broncos could retain two of their three tight ends, or find one or two tight ends on the open market, there would be less pressure to take a tight end in the draft.

This year's rookie crop offers potential answers, but also scarcity. Prospects like Minnesota's Maxx Williams, Florida State's Nick O'Leary and Clive Walford of Miami (Fla.) represent solid value at some point between the end of the first and the end of the second rounds, but there is a dearth of quality depth at the position, and beyond that trio, little hope for a plug-and-play rookie. As a result, even average tight ends on the market will attract interest.

UNRESTRICTED FREE AGENTS

JORDAN CAMERON, CLEVELAND:His ceiling was obvious in 2013, when he earned a Pro Bowl trip after grabbing 80 passes for 917 yards and seven touchdowns, and although he was limited last year, he still averaged 17.7 yards on just 24 receptions. But of greater concern than his lack of production for a team with quarterback issues was the concussion that kept him out for five games last year. It was his third concussion in a two-year span, leading to obvious concerns about his future health.

CHARLES CLAY, MIAMI (NOTE: HE WAS GIVEN A TRANSITION TAG MONDAY):By tagging him, the Dolphins effectively set his annual salary bar at $7.057 million -- and it might take more than that to prevent Miami from exercising its right to match an offer and keep him with the Dolphins. Clay is a particularly attractive prospect because of his background as a fullback, but in the last two years emerged as one of the most productive pass-catchers at the position. In 2013-14, Clay had 127 receptions, more than all but five tight ends.

JERMAINE GRESHAM, CINCINNATI:The most steadily productive second-contract tight end in this year's free-agent class, Gresham grabbed 280 passes for 2,722 yards and 24 touchdowns during five Bengals seasons, but looks headed toward the door as the Bengals look to get 2013 first-round pick Tyler Eifert more repetitions. Despite his 6-foot-5, 260-pound frame, Gresham sometimes struggled as a run blocker in recent years, and his per-catch average of 7.4 yards in 2014 was the lowest of his career -- in part because his average yardage after the catch dropped from 5.77 in 2013 to 4.10 last year.

OWEN DANIELS, BALTIMORE:He enjoyed a solid bounce-back season with the Ravens, following Gary Kubiak there from Houston and catching 48 passes for 527 yards and four touchdowns. Two-thirds of his receptions went for first downs, in line with his career first-down rate of 67.4 percent. The 32-year-old can still make plays in traffic, and has spent his entire career working under Kubiak. He also has not fumbled in over five years.

NILES PAUL, WASHINGTON:He saw more playing time last year than his first three seasons, and delivered solid production, catching 39 passes for 507 yards and a touchdown in seven starts, playing in all 16 games. Paul bulked up from 224 pounds to 241 over his four years in Washington as he converted from wide receiver to tight end, but is still a raw blocker and operates best when lined up a few yards outside the tackle.

OTHERS OF NOTE:

Lance Kendricks, St. Louis
Matt Spaeth, Pittsburgh
Bear Pascoe, Atlanta
Tony Moeaki, Seattle
Dante Rosario, Chicago
Ed Dickson, Carolina
Rob Housler, Arizona

STREET FREE AGENTS:

JAMES CASEY, EX-PHILADELPHIA:Never underestimate the value of versatility. With the ability to provide depth at tight end, line up at fullback or H-back and contribute on special teams, he could end up meeting with as many as seven teams before his whistle-stop tour ends.

ANTHONY FASANO, EX-KANSAS CITY: Released last week, Fasano has experienced a slow decline and by the end of the 2014 season was supplanted by Travis Kelce. His starting days might be behind him, but he could provide experienced depth.