Jason Witten will officially retire wearing a Dallas Cowboys' jersey, and neither side could be more pleased.

After committing only to returning for the 2017 season and mulling his future beyond that point, the All-Pro agreed to a four-year extension good through the 2021 campaign -- essentially guaranteeing he'll never wear another NFL uniform. His new deal is structured in a way that helps the Cowboys see salary cap relief when needed, proving yet again he's the consummate team player.

Here is the annual breakdown, via ESPN:

2017: $7.4 million base salary

2018: $5.75 million base salary, up to $750,000 in 46-man roster bonuses

2019: $5 million base salary, up to $1.5 million in 46-man roster bonuses

2020: $4.5 million base salary, up to $2 million in 46-man roster bonuses

2021: $3.5 million base salary, up to $3 million in 46-man roster bonuses

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Witten has a base of $26M overall with a max value of $29.6M. The latter can only be achieved if the teams lands in the playoffs each year after 2017. As it stands, his cap hit for the coming season of $12.62M will not change, but he'll only ding the cap for $6.95M per year over the remainder of his contract.

The contract comes sans signing bonus which virtually eliminates any worry regarding potential dead money in the future. With the decreasing annual base salary tethered to an increasing active roster bonus structure -- the Cowboys are buffered mightily against retirement or injury as he gets up in age.

This is paramount because although Witten has proven to be the team's resident ironman, the fact is he'll be 39 years of age if he plays out the extension -- a fact that can not be ignored.

One last addendum to the agreement sees Witten making up to an additional $900K per year from 2018-2021 should he catch 55 passes and the team, as stated above, makes the playoffs those seasons. The 14-year veteran is on pace to hit those numbers going forward as he remains a key part of the Cowboys' offense, averaging 70.75 receptions over his last four seasons.

The structure of this contract is masterful in its execution by the Dallas front office, as it rewards Witten mightily while also protecting the club's finances/salary cap and depth chart. Remaining a Cowboy will also go a long way in the grooming of a potential successor, something the team is well-aware it lacks.

It's a fitting final chapter for a marriage that's been so perfect for the last decade and a half.