We recently broke down the top keystone players the Dallas Cowboys should build their franchise around in 2019. By narrowing our list of keystone players down to five, a number of talented and productive members of the Cowboys' 2018 roster missed the final cut.

These stars are important pieces for the team and have been integral to Dallas' recent success, but they failed to make our top-5 list for good reason. The latter two players have something to prove to the team next season, while the first player's NFL career hinges on his performance in 2019 — provided he decides to return to the field:

3. LB Sean Lee

Sean Lee, Cowboys

32-year-old linebacker Sean Lee has been the heart-and-soul of the Cowboys' defense for years. Unfortunately, the former All-Pro LB can't stay healthy, which cost Dallas numerous victories and over $10 million in lost salary over the course of his career. Cowboys rookie linebacker Leighton Vander Esch's emergence in 2018 made Lee a luxury as opposed to the necessity he was to the team in prior years.

If Lee chooses to return in 2019 but isn't willing to restructure his contract, the Cowboys will face a difficult decision over the offseason — pay the oft-injured linebacker another $10 million for a final season with the team, or take a $3 million cap hit and part ways with the fan favorite.

2. LT Tyron Smith

The Dallas Cowboys' front office certainly viewed left tackle Tyron Smith as the type of keystone player the team should build their franchise around when they signed the stud offensive lineman to an eight-year, $110-million contract extension prior to the 2014 season. So far, the Cowboys have gotten their money's worth with Smith's expensive contract, but four years later, the top tackle has begun to show the effects of aging and injury.

When healthy and at full strength, Smith is a relative value at his current cost, but it's not a given that he'll make it to the end of his current deal, which expires in 2023. Since releasing Smith after the 2020 season would have little cap implications for the Cowboys, if the offensive lineman can't remain healthy and productive, Dallas could begin their search for his replacement next year.

1. QB Dak Prescott

dak prescott, kellen moore

Quarterback Dak Prescott is probably the most important player on the Cowboys' roster because he plays the most important position on the team, and he plays it at an extreme discount compared to other starting QBs because his salary is tied to his late-round draft status.

Prescott would have topped our list of Dallas Cowboys keystone players if the team was able to retain him at his current salary, but the quarterback is in line for a hefty raise at the end of his rookie deal. The Cowboys will have their first opportunity to re-sign their starting QB in the coming months, and Prescott strengthened his case for a long-term extension with improved play in 2018.

But if Dallas waits a year before addressing Dak's looming contract expiration, Prescott will need to play like a franchise quarterback in 2019 if he expects to command the salary of a franchise QB.