In the NFL, the backup is only one play away from being the starter.

That goes for all positions, but it may not be as important as it is with the quarterback. When the starter goes down, all hell can break loose because they’re the “glue guy” for the offense.

The quarterback knows every play, and every assignment of every player. He also must know his teammates’ tendencies; how they run routes, where they like the ball placed, the timing needed to complete the pigskin.

For the Denver Broncos, the problem of finding a legitimate starting quarterback was solved this offseason when they signed Case Keenum. Without a doubt, Keenum has lifted the spirits of Broncos fans while also lifting the team’s expectations a bit as well.

But, what if Keenum goes down and is injured? Even for a game, leaving the offense in the hands of Paxton Lynch (first) or Chad Kelly would likely come with disastrous consequences.

Lynch is now entering his third season and continues to look lost on the field, and Kelly looks worse, unfortunately.

“[They’re] very solid,” Vance Joseph said of the two backups on July, 31. “It’s early, it’s practice, so no one is grading practice. We don’t look at it like you guys look at it. It’s just practice, so we have good plays, we have bad plays, and we fix the bad ones and high five the good ones. We’re not taking stats, we’re not grading guys right now, we’re just coaching.”

Interestingly, with the Broncos set to kick off their preseason against the Minnesota Vikings tomorrow (7 p.m. MST), Cody Roark asked the question of Broncos fans earlier today, and a majority (so far) believe Denver needs to go sign a veteran backup:

So, who are the best free agent quarterbacks on the market currently? Let’s take a quick look.

Matt Moore

Moore has been a solid backup in the NFL for 10 years. Over the last two seasons, he was asked to play in eight games for the Miami Dolphins, totaling 1,582 yards and 12 touchdowns compared to eight interceptions.

Derek Anderson

Anderson is even older than Moore (34) at 35 years old, but he was a solid starter back in the day and would be a decent backup to have on the team. With his 12 years in the league, he’s seen just about everything. In 2016, he started twice for the Carolina Panthers and threw for 453 yards with two scores and five picks.

Johnny Manziel

Manziel has gone through his fair share of problems, and now he’s up North (eh!) playing for the Montreal Alouettes. His CFL debut last week set the record for most-watched Canadian Football League game in history, with an average of 400,000 viewers. He threw four picks, though, and there’s no guarantee he could be turned around on or off the field.

Mark Sanchez

Again? Probably not. But, you never know.

Colin Kaepernick

Anyone who cannot see Kaepernick is the best unsigned quarterback in the world right now is looking through politically fogged glasses. Simply, the former starter for the San Francisco 49ers in “Kaep” could start today for 10-plus teams. In fact, the Broncos should have signed him last year, but he would have likely turned out to be the best quarterback on the team and have to be promoted to starter. He may not be good enough to beat out Keenum, but he’d be a wonderful Plan B. had him as the ninth-best free agent QB going into this offseason and the only one in their top-13 who isn’t signed still.

In his last year with the Niners (2016), Kaepernick threw for 2,241 yards with 16 touchdowns and four interceptions. He also ran for 463 yards and two scores.