Kathy Willens/Associated Press

In just a few weeks, the 2014 NFL season will be complete and attention will shift to free agency. For the Philadelphia Eagles, this is something that head coach and de facto general manager Chip Kelly already started thinking about weeks ago.

After losing three of their final four games to miss the postseason after a 9-3 start, the Eagles have already begun what will likely be a very dramatic offseason. A brief power struggle came to a close, as former general manager Howie Roseman was essentially given a demotion with a pay raise. He's the new vice president of football operations, and Kelly has complete control over all football matters.

That matters, because Roseman has proven that he has an eye for building the team through both free agency and the draft. Now it's all up to Kelly. While he's still a question mark in the draft, he's had some solid free-agent signings. His most notable include pass-rushing linebacker Connor Barwin, safety Malcolm Jenkins and special teams acquisitions like Chris Maragos and Bryan Braman. Mostly though, he's picked mid-range players like Cary Williams instead of stars like Darrelle Revis and Jairus Byrd.

This is a critical offseason for the Eagles because Nick Foles enters the final year of his contract. If they believe they can win the Super Bowl with Foles, they could look to sign him to an extension either this offseason (not likely) or next offseason (likely). Depending how close the Eagles believe they are to competing for a Super Bowl title, they could be heavy spenders or light spenders in free agency.

According to ESPN's NFL Insider Adam Schefter, the NFL believes the 2015 salary cap will be between $138.6 million and $141.8 million. The NFLPA believes a substantial increase will be added, with the league potentially adding $10 million more to the projected $140 million total.

This offseason, the Eagles will carry over $15,757,296 in salary-cap space from the 2014 offseason, the third-highest figure in the National Football League, per Over the Cap. They have $136,001,156 committed to players for the 2015 salary cap. That's $69,471,882 on the offensive side of the ball, $62,626,686 on defense and $3,663,333 on special teams.

The Eagles can also clear up some more space by either cutting veterans or asking them to restructure their contracts. Among them include running back LeSean McCoy ($11.95 million), tight end James Casey ($4 million), guard Todd Herremans ($5.2 million), inside linebacker DeMeco Ryans ($6.8 million), outside linebacker Trent Cole ($11.625 million) and cornerback Cary Williams ($8.16 million), per Eagles Cap.

The Eagles will probably try to keep three or four of those six players, but by restructuring a few of the contracts, they could likely save close to $20 million in space. It makes sense to keep McCoy, Herremans, Ryans and Cole. They're all still solid starters, and it'd be pretty difficult to replace any of them by next season.

That puts the Eagles around $36 million, but they still need to take care of their own free agents.

Jeremy Maclin is a lock to earn a long-term contract extension. He'll probably be signed for about five years, $45 million and $12 million guaranteed. That's $9 million a year, and it's a very similar deal to the one the Eagles gave DeSean Jackson before the 2012 season.

Other Eagles free agents who could be re-signed include quarterback Mark Sanchez, running back Chris Polk, defensive end Cedric Thornton and safety Nate Allen. I'd bring back two or three at a total cost of about $7 million.

Fletcher Cox and Mychal Kendricks each enjoyed breakout years during their third season in the league. Both 2012 draft picks will undoubtedly be extended for at least five years. If Cox and Kendricks each earn about $7 million per season, that's another $14 million.

Other candidates for contract extensions this offseason are Nick Foles, Vinny Curry and Brandon Boykin. But it makes no sense to extend any of those three before the 2015 season. Let them enter the final year of their rookie deal without an extension and see what happens.

At this point, the Eagles will have about $6 million to spend in free agency, plus their draft picks, although don't be surprised if Howie Roseman is able to spread out the contract extensions so the initial hit isn't as extreme. Realistically, the Eagles are probably looking at about $13 or $14 million to spend in free agency.

Even with their well-publicized offensive struggles in 2014, the Eagles scored 474 points, the most in team history. It doesn't make sense to sign a starter on the offensive side of the ball. It really doesn't. It has to be tempting if a big-name receiver like Demaryius Thomas or Randall Cobb hits free agency, but that's more of a want than a need. The Eagles will be fine with Maclin, Matthews, Huff and company. They absolutely need defensive help.

The defensive line is fine, with Bennie Logan, Fletcher Cox, Vinny Curry and Cedric Thornton. It's linebacker, cornerback and safety where the Eagles desperately need help.

One or both of Trent Cole and Brandon Graham will not be returning to the team in 2015. Options for free-agent outside linebackers include Jason Worilds, Brian Orakpo, Brooks Reed and Sam Acho. Worilds almost signed with the Eagles last year before the Steelers gave him the franchise tag. He'd be my target, although the Eagles are also familiar with Orakpo after watching him in the NFC East since he was drafted. And Acho is the brother of current Eagles linebacker Emmanuel Acho.

At cornerback, the top options include Byron Maxwell, Antonio Cromartie, Kareem Jackson, Chris Culliver and Perrish Cox. I left off Darrelle Revis because I don't expect the future Hall of Famer to leave New England. Even if he does, I don't think the Eagles will go after him. He turns 30 this offseason, and he's just too expensive. Sign a mid-range player like Maxwell or Jackson and you hopefully have a starter for the next three seasons. Then again, Cary Williams and Bradley Fletcher were mid-range options and that didn't work out at all.

The final necessary upgrade for the Eagles is safety. There's one player the Eagles should definitely target, and that's converted cornerback Devin McCourty. McCourty will be 28 next season, so a four-year deal seems practical. Realistically though, the New England Patriots will either re-sign or use the franchise tag on McCourty. Other options at safety include Rahim Moore, Antrel Rolle and Da'Norris Searcy.

If the Eagles can get two players from the three positions, that will be considered a success. Free agency is always a tricky period for teams because there's always a reason a player is allowed to hit free agency. He's always played at least four seasons so he'll have mileage. He's never going to be a superstar, and if he is, there's usually a glaring reason why the team allowed him to leave.

The Eagles have always been one of the top teams in the NFL when it comes to spending their money. It'll be interesting to see how things change with Kelly running the complete show. According to Reuben Frank of CSNPhilly.com, the Eagles say that Roseman is still in charge of handling contract situations, but it remains to be seen what will happen if Kelly and Roseman disagree over the amount a player should be paid. Then again, you can probably guess who will win that one.

With the Eagles reeling after their late-season collapse, Chip Kelly will have to analyze how close this team is to becoming a Super Bowl contender. If he thinks they're close, it makes sense to spend some money. Even if he doesn't think they're quite ready, it's time to plug some of those glaring holes on the defensive side of the ball, especially in the secondary. The Eagles have money. Spend it.