FRISCO, Texas -- Mark Sanchez will eventually be the Dallas Cowboys' backup to Dak Prescott while Tony Romo is out with a compression fracture in his back.

Sanchez agreed to a one-year deal, a source told ESPN’s Adam Schefter, a few days after the Denver Broncos attempted to trade him to the Cowboys.

The Cowboys felt like they had to do something behind Prescott, who will become just the fourth rookie in franchise history to start a season opener. Roger Staubach started the 1969 opener. Troy Aikman started the 1989 opener. Quincy Carter started the 2001 opener.

For those who live in the world of conspiracy theories, know this: Head coach Jason Garrett and offensive coordinator Scott Linehan have the same agent as Sanchez in David Dunn.

Last year, the Cowboys somewhat surprisingly added Kellen Moore to their practice squad after the final cuts. His agent? Dunn. When the Cowboys lost Tony Romo in Week 2 to a broken left collarbone, they made a trade with the Buffalo Bills for Matt Cassel. His agent? You guessed it, Dunn.

It’s further proof that who you knows matters in the NFL, just as it matters in any walk of life.

Given Sanchez's $4.5 million base salary, a trade between the Broncos and Cowboys was not going to happen. Plus, the Cowboys did not want to give up a draft pick for a player they knew would be cut in a few days. The salary and the Cleveland Browns' asking price kept the Cowboys from pulling off a trade for veteran quarterback Josh McCown after Moore went down Aug. 2 with a broken fibula. McCown is not represented by Dunn.

The Cowboys visited with Austin Davis, who also isn’t represented by Dunn, last Wednesday and hoped he would sign on to be Prescott’s backup in Romo’s absence. Instead he was looking for some serious commitment to join the Cowboys when he was less than a week from being cut as the Cleveland Browns’ fourth quarterback.

So four days later, the Cowboys have an agreement with Sanchez.

Sanchez's experience gives them some cover if Prescott should falter. Of course, they thought the same of Cassel and he had difficulties getting the ball down the field. Sanchez has a 37-35 record and helped the New York Jets to the playoffs twice, including an appearance in the AFC Championship Game in 2009.

But he has 86 touchdown passes and 84 interceptions. In the preseason with the Broncos, he completed 20 of 30 passes for 219 yards with one touchdown and one interception. He lost the starter competition to Trevor Siemian and the backup competition to Paxton Lynch, whom Cowboys owner and general manager Jerry Jones regretted not doing more to acquire in a draft-day trade.

It remains possible the Cowboys keep Jameill Showers around for at least the first week of the season because of his familiarity with the offense. It also remains possible they put Romo on injured reserve as soon as today.

If the Cowboys need quarterback help later on in the season, it might be best to check out Dunn’s client list.