In some ways, NFL front offices have it easy: Thanks to the collective bargaining agreement, a team that finds a good player outside of the first round of the draft gets to keep him at a bargain until the end of his rookie deal.
One way of seeing just how much of a steal teams are getting is by using my Jahnke Valuation Model (JVM), which measures how much money a player should have made based on the quality of his play. It takes into account how well the athlete played compared to other players at the same position, and how much money teams devote to that position. It is based completely on their 2013 performance, so it doesn't take into account previous years, and is not meant to gauge how much they should earn in the future. In general, it is just a tool for measuring how much money a team was overpaying or underpaying for a player for the season.
On Monday, I used the model to see which 10 players were overpaid the most based on their 2013 performance. In this file, I'll use it to identify the 10 most underpaid players.
What follows is a list of 10 players with the largest negative discrepancies in how much they were paid in 2013 compared to how much they should have gotten paid. As such, here is our ranking of the NFL's 10 biggest bargains from 2013:

1. Russell Wilson, QB, Seattle Seahawks
2013 cap hit: $700,000
2013 JVM: $15.5 million
Value differential: $14.8 million
The Seahawks are getting a tremendous deal on Wilson's contract, and as a result they have been able to invest heavily in other areas. Wilson deserves to get paid like one of the top quarterbacks in the league. He doesn't put up a lot of 300-yard passing games, but he was one of the most accurate passers on deep throws in 2013, and posted 922 passing yards on throws of at least 20 yards, which ranked fourth in the league.
For the second straight year, Wilson was among the top five undervalued players in the league (and last year was the second straight season that he ranked as the NFL's most undervalued quarterback). If I had to bet on one player to be the most undervalued in 2014, it would be Wilson.