Tom Brady Reportedly Leaves Millions on Table, Sticks With Patriots

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It appears like quarterback Tom Brady will finish his football career where it started, with the New England Patriots.

Reports are that the three-time Super Bowl winner has agreed to a three-year contract extension that keeps him with the team through the 2017 season.

The value? About $27 million.

That sounds like a lot, but in terms of the open market for superstar quarterbacks, it's probably less than a year-and-a-half of salary for three years of work.

Why did he leave so much money on the table?

First of all, because he can. Brady is worth an estimated $100 million dollars — wife Gisele Bundchen is worth even more — and most likely, on the heels of his success and good looks, Brady will be able to pitch products for most of his adult life.

The second reason he accepted at least $25 million less than what he could've earned is that Brady is aging. The 35-year old always has said that he wanted to do two things: Play until he was 40 and finish his career with the Patriots.

With this deal, he accomplishes both.

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However, the key here is how good the team is in that time. A lower salary for Brady means more money to spend on other players, such as his favorite target, Wes Welker, who is a free agent.

"Some of this is selfish, too," said Dr. Patrick Rishe, a sports economist at Webster University in St. Louis. "Brady loves tossing the rock to Welker. He realizes that his own success is enhanced by having familiar and dynamic players surrounding him."

That is even more important over the next few seasons because Brady wants another title, and there won't be any meaningful expansion in the salary cap. Without Brady taking a hometown discount, the Patriots would have been faced with difficult decisions.

One of them may have been whether to jettison Brady himself.

Put it this way, if he wanted a contract commensurate with his performance and his cohort, Brady would earn somewhere near $20 million a year in a new deal. That's the average of Dree Brees' deal with New Orleans, and it's the amount Super Bowl MVP Joe Flacco is targeting from the Baltimore Ravens.

However, if the Patriots paid him that amount, the team would be hamstrung almost everywhere else on the roster.

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Hence, they would be faced with two options: Have Brady and no depth. Not have Brady and have depth. Neither are good scenarios.

Fortunately for Patriot fans, Brady ensured neither will happen. All because he turned a cliche on its head. When people say, "It's not about the money," it usually is.

For Brady, it seems it's not just about the money.

—By CNBC's Brian Shactman; Follow him on Twitter: @bshactman