Value is defined by, the regard that something is held to deserve. Teams in the NFL constantly try to maximize their rosters by finding guys who are useful but come at the cheapest price possible.

That's why teams in the NFL who have young quarterbacks are racing to build a talented roster around him. With their quarterbacks on rookie deals, they're able to sign stars at other positions to fill out their rosters a bit better.

Then, on the other hand, there are players who aren't being paid according to their production. Some of the players are even considered the best at their position among their peers. This can be true even for players who are in their 30s.

Here are three players (among many) who are 30-years old or older who are underpaid by their current teams.

3. Jason Kelce

Jason Kelce, Eagles
CP

This offseason, the Philadelphia Eagles began with little to no cap-space available. Thanks to veteran players like Jason Kelce though, the team was able to free up money to improve their roster. At 31-years old, Kelce is still playing at the top of his game.

Kelce is undeniably one of the best centers in the NFL and has been a mainstay on the Eagles offensive line since being taken in the sixth round of the 2011 NFL Draft. The center position is vital to every offense being on the same page as they are considered the quarterbacks of the offensive line.

The Eagles center has started in 73 straight games and is a force to be reckoned with in the running and passing attack in Philadelphia. For the most part, Carson Wentz is able to keep his jersey clean thanks to Kelce and the other offensive linemen.

Kelce is due just $930,000 in 2019 and just $7 million combined in his last two seasons on his contract. In 2019, Kelce is the 24th highest-paid center in the NFL but should be paid like a top-five center.

Jason may not get the recognition that his brother Travis does but Jason is one of the best at his position as well.

2. Mitchell Schwartz

Mitchell Schwartz
Clutchpoints

Another offensive lineman cracks the list and at number two with the Kansas City Chiefs right tackle with Mitchell Schwartz. With Patrick Mahomes shining with 50 touchdowns last season, people finally took notice of Schwartz on the offensive line.

To some people, the right tackle may not be a fancy position but guys like Schwartz are crucial to his team's success. After all, protecting the quarterback is the most important job anyone can have as quarterbacks are the most important position.

Before joining the Chiefs in 2016, Schwartz began his career with the Cleveland Browns in 2012—playing on the opposite side of Joe Thomas. Nonetheless, Schwartz has never missed a game in his career—starting in 112 straight games.

In 2019, similarly to Kelce, Schwartz is set to make $930,000—making him the 11th highest-paid right tackle this year. Then, in 2020 and 2021 he'll make nearly $10 million in those two seasons combined.

Schwartz is arguably the best right tackle in the NFL but he isn't paid like one.

1. Julio Jones

Julio Jones
CP

The Atlanta Falcons recently gave Grady Jarrett a long-term extension but Julio Jones is probably wondering where his is. The All-Pro wide receiver is still playing at an unbelievable level but isn't getting paid nearly his worth.

Last season, Jones caught 113 passes for 1,677 yards and eight touchdowns. Jones was top-five in just about every statistical category among receivers while leading all receivers in yards.

Coming into this season, Jones is entering the second-to-last year on his current deal. The Falcons wide receiver is set to make $9.6 million in 2019 and $11.4 million in 2020.

This season, Jones is expected to be the 13th highest-paid receiver in the NFL. Jones will make less money than the likes of Sammy Watkins and Allen Robinson.

Both of those guys are talented but they're not on Jones' level.