Dak Prescott is the unquestioned starter in Dallas, and his metoeric rise to the top of the depth chart had almost everything to do with Tony Romo's serious back injury last season, which lead to his eventual retirement. Injuries are as much apart of football as the forward pass, and as the Cowboys learned in 2015, the year before Prescott arrived, there needs to be a backup plan in place should the starter go down.

Romo played just four games that season, and the options behind him -- Brandon Weeden, Matt Cassel and Kellen Moore -- weren't even replacement-level fill-ins. When it was over, the Cowboys were 4-12, with Romo managing three of those wins.

With training camp underway ahead of the 2017 season, Moore remains on the roster, along with undrafted rookie free agent Cooper Rush and Zac Dysert, a 2013 seventh-round pick of the Broncos. But Dysert is out with a herniated disc in his back, and with the Cowboys' first preseason game less than a week away, the team agreed to terms with 36-year-old Luke McCown.

The Cowboys will be McCown's sixth NFL team -- he has also played for the Browns, Buccaneers, Jaguars, Falcons and most recently, the Saints -- though he's never started more than four games during his 13 NFL seasons.

McCown signed a two-year deal with the Saints in March 2016 but was released in  April. How long he remains in Dallas is an unknown, but Cowboys coach Jason Garrett said this week that, for the time being, he is happy with Prescott, Moore and Rush. But with Prescott not expected to see much time in next Thursday's Hall of Fame Game, keeping McCown around for a while makes sense.

McCown's brother, Josh, is currently a quarterback on the Jets roster. He's played for 10 NFL teams over 14 seasons, though never for the Cowboys.