Former Denver Broncos and New York Jets quarterback Tim Tebow remains on the comeback trail, hoping to make an NFL roster. And even though critics have panned his ability to lead a team under center, there is a chance the 26-year-old Heisman winner can make a team at some point in the upcoming season.

For one, the market for back-up quarterbacks is rather thin right now. That has more to do with teams carrying three or four quarterbacks during training camp, with at least one or two expected to be cut before they trim down to a 53-man roster. However, teams are keeping their options open, and Tebow said in a recent interview that NFL teams have contacted his agent, though Tebow didn’t go into detail.

One NFL head coach recently went on the record as an admirer of Tebow’s.

“I’m a big fan of his and he knows it. He has always given me fits when I’ve had to coach against him,” Carolina Panthers head coach Ron Rivera said according NESN. “He’s a playmaker and he plays a different kind of football. All the guy has ever done is win. … He’s one of those guys if you were struggling at quarterback, hey, why wouldn’t you give him a shot?”

Giving Tebow a shot during training camp is one thing, but many teams learned the hard way that you never know when a backup quarterback will be needed. In the 2013 NFL season, 63 quarterbacks attempted at least one pass, a high number considering teams like the Cincinnati Bengals, Carolina Panthers, Detroit Lions and San Diego Chargers did not sit their starters the entire season. In the first half of the 2013 season, 11 teams used a reserve quarterback.

Presently, some of the available veterans include former Cleveland Browns, St. Louis Rams and Denver Broncos quarterback Brady Quinn, Super Bowl starter for the Chicago Bears Rex Grossman, Green Bay Packers' backup from last season Seneca Wallace, 2009 Pro Bowler David Garrard, and 16-year journeyman Jon Kitna. A hodgepodge list filled with players who had success, but are now clinging to the NFL’s backburner.

Tebow hasn’t played since 2012, following a failed stint with the Jets, and he was cut from by New England Patriots in the final week of the preseason last year. But if teams take a look at how in shape and focused he is, they’ll see Tebow is a capable dual-threat passer with a solid touchdown-to-interception ratio (17 to 9), and 20 career rushing touchdowns. He can certainly extend and make plays, represented by his six fourth-quarter comebacks, five of which came with Denver in 2011.

Let’s take a look at the other available backup quarterbacks, and what they can bring to a roster.

Brady Quinn

A first-round draft choice of the Browns back in 2007, Quinn famously flamed out in Cleveland and had his last real shot with Kansas City back in 2012, going 1-7 in eight starts with two touchdowns to eight picks. Like Tebow, Quinn hasn’t quite given up on his NFL aspirations. He reportedly worked out for the New England Patriots on Monday, but his chances of joining them in camp are slim especially with Ryan Mallett already on the roster.

Rex Grossman

After starting 13 games in Washington in 2011, Grossman rode the bench for the last two seasons following Robert Griffin III’s arrival and Kirk Cousins usurping the backup role. He nearly helped Chicago win its first Super Bowl in 20 years back in 2006 with a 13-3 record, despite throwing 20 interceptions compared to 23 touchdowns. But that proved to be his best season as a starter, and Grossman has never had a defense like the 2006 squad.

Seneca Wallace

A star at Iowa State, Wallace followed Mike Holmgren from Seattle to Cleveland but couldn’t hold down the starting gig after going 2-6 in seven starts with six touchdowns to four picks. He sat out 2012, and caught on with the Packers, filling in for the injured Aaron Rodgers in one start. The 34-year-old did complete 66.7 percent of his passes, but only took 24 pass attempts in three games.

David Garrard

As Jacksonville’s starter from 2006 to 2010, Garrard compiled a 39-37 record with 89 touchdowns to 54 interception, and averaged a 61.6 percent completion rate. However, serious knee injuries were Garrard’s downfall, and he fell off before landing with Miami and eventually the Jets. He planned to call it a career in May 2013, but he’s evidently still on the market for interested teams.

Jon Kitna

The most experience of all the free agents, Kitna might have a losing record as a starter (50-74) and has thrown only four more touchdowns (169) than interceptions (165) in 16 years, but he’s a proven leader in the locker room who can rally a team behind him. In 2010, he last started nine games for the Cowboys, winning four, and lifting a Dallas team that had gone 1-7 in its previous eight games.