Watch Now: Report: Cowboys, Dak Prescott Fall Short In 'Last Minute' Negotiations (2:08)

After using the franchise tag on Dak Prescott in March, the Dallas Cowboys had until July 15 to hammer out a long-term contract with their starting quarterback, but that didn't happen, which means that Prescott will now be playing the 2020 season on a one-year deal that will pay him $31.4 million. Although the Cowboys are set at quarterback for the upcoming season, their inability to get a deal done by the tag deadline could end up having a dramatic impact on things down the road, and if NFL history is any indication, there's a good chance that Prescott might not be in Dallas much longer. 

Since the franchise tag was first instituted in 1993, only two quarterbacks have played a season on the tag and both players ended up leaving their teams. The first case happened with Drew Brees back in 2005. After Brees and the Chargers couldn't agree to terms on a long-term deal, the team ended up hitting the quarterback with a non-exclusive franchise tag that would end up paying him $8 million. After the 2005 season, the Chargers were hesitant to give Brees a long-term deal because he was dealing with a serious shoulder injury that required surgery. During free agency, the Chargers lowballed Brees, offering him just $2 million guaranteed, which was an embarrassingly low offer compared to the $10 million that the Saints were offering. (You can read a deeper dive on Brees' free agency by clicking here.) After briefly contemplating a return to the Chargers and flirting with the Dolphins, Brees ended up taking the offer in New Orleans. 

The other quarterback to play under the franchise tag was Kirk Cousins, who did it with the Redskins in both 2016 and 2017. During those two seasons, Cousins was paid a total of $44 million ($20 million for 2016 and $24 million for 2017). Like Prescott, Cousins was a fourth-round pick who didn't get an offer he liked from his team. In the end, Cousins ended up leaving town to sign a fully-guaranteed three-year, $84 million contract with the Vikings

The problem for the Cowboys is that Dak's price is only going to keep going up. Prescott was eligible for a contract extension after his third year in the league (2018) and Dallas likely could have gotten a deal done then with an offer of $34 million per year. At that point, that amount would have made Prescott the highest-paid quarterback in the NFL, which is why he might have taken it. However, the market has shot up over the past 12 months, thanks in large part to Patrick Mahomes and his $503 million contract.

If the Cowboys want to keep Dak, it's going to cost them at least $37.7 million in 2021, because that's how much it will cost to franchise tag him for a second time (the second tag gives the player a 20% increase over his salary from the prior year). If the Cowboys hit him with a third tag, his salary would balloon to $54.3 million in 2022, since the third tag gives the player a 44% increase over his salary from his second tag. 

At those numbers, Dak would be making an average of $46 million per year for 2021 and 2022, which is money the Cowboys might not be willing to pay, and now, you can see why things haven't been working out for teams that try to keep their quarterback by using the franchise tag. 

The idea of Dak leaving Dallas seems to be very real to at least one member of the Prescott family, and that's because Tad Prescott, Dak's brother, insinuated on Wednesday that he doesn't know how much longer Dak will be with the team.

Overall, the franchise tag has only been used a total of 11 times ever on a quarterback, including Prescott. In eight of those situations, the two sides ended up working out a long-term deal, with the most recent signing coming in 2011 when Peyton Manning agreed to a five-year, $90 million contract with the Colts. Brees and Cousins are the only two that played out the one-year deal, and they eventually left town. 

For a deeper look at all the questions that remain following the Cowboys' inability to get a deal done with Dak, be sure to click here to check out our CBSSports.com story by former NFL agent Joel Corry.