PHILADELPHIA (973espn.com) — Howie Roseman's offseason strategy has been evident to anyone paying attention, identify the core pieces on his team and lock them down with team-friendly contract extensions.

For the most part the Eagles' executive vice president of football operations has been able to do exactly that with one notable exception, Pro Bowl defensive tackle Fletcher Cox, unquestionably the club’s best player.

That said, Roseman's negotiations with Cox always shaped up as far more difficult because the Mississippi State product is already set to make significant money this season on the final year of his rookie deal ($7.8 million) and, if he has another big year, Cox could really cash in, a reality that Roseman hasn’t run from.

“We talked about Fletch, he’s still on our to-do list, there’s no question about that,” Roseman said earlier this offseason. “We’re not forgetting about that or him.”

According to two NFL sources the Eagles have pegged Cox’s worth at somewhere between $12 million and $14 million a year but if you look at the success new defensive coordinator Jim Schwartz has had with under tackles in his 4-3 scheme, Cox’s projected position, that number could rise significantly after the 2016 season if Cox feels like betting on himself.

With most of their work in free agency done, the Eagles are currently $10.8 million under the cap, according to NFLPA figures. And that’s where the inventive Roseman comes in because both Cox and the rookie class remain on deck.

“We have to make sure that we’re always in a place to be able to get Fletcher done,” Roseman said. “So anything we do, it’s in the back of our mind that we want to get Fletcher done. Whether that’s today, tomorrow, whatever point in time, we want Fletcher to be here.”

Signing a long-term deal with significant guaranteed money spread over a five- or six-year period with base salaries that explode on the back end cold make the ensuing salary-cap hits in the early years manageable, while setting up a renegotiation scenario in say year four of the deal.

On Monday morning FOX29's Howard Eskin appeared on the NFL Network and claimed the Cox camp, led by veteran agent Todd France, has already turned down a massive $60 million in guaranteed money from the Eagles, the same number paid to Ndamukong Suh before the 2015 season and the highest ever given to a defensive player.

"It's ridiculous because Fletcher Cox ... a lot of these guys, they listen too much to their agent," Eskin said. "His agent is Todd France. The Eagles, I have been told, have offered him over $60 million guaranteed. Now that the contract would be worth over $100 million.

"But Todd France has told Fletcher Cox not to accept that, and that's ridiculous because the Eagles could have his rights for three years. The year of the contract left this year, they can franchise him two more years, $60 million guaranteed. Fletcher Cox is not a guy that spends a lot of money, but Todd France represents other defensive lineman. So, and people believe this in football, that he's trying to get an unbelievable deal for Fletcher Cox so his other players' scale of salary would increase and use this to try and get those guys more money.

"It’s ridiculous that Fletcher Cox has not signed a contract which guarantees him over $60 million. And a couple years ago, he had some back issues and, I mean, any player can go down, so that’s the problem. The Eagles have offered him a lot of money and his agent, Todd France, said "Nope." And I think he’s using Fletcher Cox for his other players down the line."

Eskin is right, it is ridiculous for Cox to turn down that kind of money so the real question is did the Eagles really agree to make Cox, a tremendous player but certainly not J.J. Watt, Von Miller or even Suh, the highest paid defensive player in the history of football?

At this stage with what Roseman has to work with under the cap, the numbers provided simply don't add up, at least without creating more space.

Meanwhile, France took exception to Eskin's claim on CBS Philadelphia.

"I’m 44 years old. You think I enjoy people — I shouldn’t say people — a person talking about me with this kind of misinformation and framing it in a certain way?” France said on the Mike and Ike Show. “No, it makes me want to be that tough guy that you guys told me I was and throw on the boxing gloves and say let’s go at it Howard, let’s go."

When you leave the personal stuff in the rear-view mirror, however, it seemed as if France was trying to explain the nuanced difference between "guaranteed money" and "fully-guaranteed money" when discussing NFL contracts.

“To say a contract is worth — whatever I’m gonna use $60 million guaranteed — and a certain amount of it he gets today, but the next year he gets some if he’s on the roster is guaranteed,” said France. “And the next year he gets it guaranteed if he’s on the roster then. And the next year he gets it if he’s on the roster — those are year-to-year guarantees.

“Any person that’s got any intelligence to the football business will write and say, ‘That really isn’t X amount guaranteed.’ Because the team can do what? Get rid of the guy and cut him at any point and that quote-unquote guaranteed money the player never really receives.”

So did Cox turn down $60 million in potential guarantees?

Probably.

Did he turn down $60 million that was fully guaranteed?

Absolutely not.

-John McMullen covers the Eagles and the NFL for 973ESPN.com. You can reach him at jmcmullen44@gmail.com or on Twitter @JFMcMullen