The Cowboys' staredown with quarterback Dak Prescott was one of the dominant storylines of this unusual NFL offseason, with the mega-deal falling apart for what sources said was an unusual reason, and with the ramifications likely looming in Dallas for years.

Conversations with general managers, agents and team contract negotiators revealed a consensus about both the magnitude of the Cowboys' mistake with this negotiation -- several sources independently suggested it will cost owner Jerry Jones roughly $40M -- and general agreement about how it will impact the team in years to come. The sides did come relatively close to completing a long-term deal by the July deadline by which to extend the contract of a player on a franchise tag, but Prescott ultimately opted to play out 2020 on that tag in a move that is being heralded throughout the industry as one that will reap tremendous financial benefits for him in 2021 and beyond.

The Cowboys were insistent on a five-year salary structure for the quarterback, who had his most productive season in 2019, is surrounded by a strong supporting cast and is drawing some preseason hype as a potential MVP candidate this season. Jones has long sought to secure his top players to the longest term possible, and while Prescott's representation was intent on four years for much of the offseason, things changed near the July deadline, according to the sources. At that time Prescott would have accepted a five-year deal, worth about $35M a year, but only if it included a provision that he could not be franchise tagged at the conclusion of the deal. Jones would not agree to that language, sources said, and the deal fell through.

Since then Deshaun Watson secured a new contract extension with the Texans worth nearly $40M a season, and Patrick Mahomes, generally seen as the best player in the game, is locked in at $45M a year for the next 12 years. Barring catastrophic injury, Prescott's market value for 2021 seems pretty clear in the estimation of these GMs, agents and cap gurus: between $42M-$43M a season. The Cowboys will have no choice but to franchise tag Prescott, earning $31.4M this season, again in 2021 to secure his rights, which would lock in a $38M salary. That alone is nearly $70M for two years -- with no team control beyond 2021 -- compared to Mahomes earning $63M in the first three years of his new deal, with the Chiefs still controlling his rights into the next decade. 

"No matter how you slice it, Jerry made a $40 million mistake," said one prominent agent who has negotiated top quarterback contracts but is not involved in Prescott's deal. "Just do the math. It's pretty simple. Prescott has them over a barrel."

"Based off everything I know of that situation, the Cowboys did themselves no favors," one GM offered. "Even when the cap goes up (expected perhaps by 2022 depending on COVID-19), $8 million a year is a big deal. That's like costing yourself a couple of starters or top backups at less-expensive positions. If you think you're competing for a Super Bowl, that's a big deal."

"This one seemed to get personal," another longtime NFL team exec said. "It should have been done before Watson and (Lamar) Jackson, whether it's four years or five years. And what happens if Prescott goes out and throws 40 TDs? The Cowboys were too stubborn for their own good."

"I don't know how Jerry was reading the quarterback market, but they read it all wrong," one salary negotiator said.

In reality, the likelihood of Prescott ever even reaching a point where a future franchise tag would matter in a five-year deal seemed remote to everyone I spoke to, with the changing NFL economic landscape and his performance setting up another extension by 2023 given the way QB contract dynamics normally work. And now it stands to cost the Cowboys dearly. 

As owner Stephen Jones said of Prescott on his radio show on Friday, "He's bet on himself, and bet wisely."