The time frame to win in the National Football League with any core group of players is tight, primarily due to the physicality of the game which causes injuries and shortens careers. That's what makes the Philadelphia Eagles collapse from the driver's seat in the NFC East at 9-3 to missing the playoffs at 10-6 extremely disappointing. The talent was there with the core group of players Chip Kelly had in his second NFL season, and the Eagles still fell short, taking a step back after making the playoffs in Kelly's first year.

Kelly started the season off well at 6-2, in control of a playoff spot, but once Nick Foles and DeMeco Ryans went down for the season against the Houston Texans, the season spiraled downhill. Mark Sanchez took over the quarterbacking duties, and was serviceable at times, and a turnover disaster at others. The dark omen of the Philadelphia Eagles season was their loss at Green Bay, where they were absolutely obliterated in all facets of the game by the Packers. Even though the Eagles beat the Cowboys a few weeks later in Dallas on Thanksgiving, there was a sense that maybe this Philadelphia team could not beat playoff-caliber teams, and then came December. Three straight losses later to the Seahawks, Cowboys, and (this is embarrassing) Washington Redskins, and the Philadelphia Eagles no longer had the ability to make the playoffs.

Sanchez played well, but Kelly's offense lost a vertical presence without Foles, a presence that is key in the offense's effectiveness. Besides Sanchez's turnover flaws that were further exposed the more he played, the Eagles secondary was man-handled once the calendar flipped to December. Before December hit, Aaron Rodgers looked like an immortal superhero when he picked a part Philadelphia's secondary, then in December Tony Romo's stellar numbers were boosted after facing the likes of Bradley Fletcher and Cary Williams, and even Robert Griffin III had flashes of his rookie season en route to beating the Eagles.

Here the Eagles sit, trying to figure out what they need to do to improve this football team. Chip Kelly and defensive coordinator Bill Davis have expressed the need to fix the defense, while Kelly has also noted that he will be diving into the quarterback situation as well. Diving into the quarterback seems useless. Eagles' players have publicly stated that they trust Nick Foles to lead them to a championship, and it is about time Chip Kelly does the same. Kelly is failing to see that he went 14-4 with Nick Foles as his quarterback, and while Foles certainly did not help his cause with his average play this season, he still went 6-2 despite turning the ball over with an injured offensive line and ineffective running game.

Age in the NFL plays more of a role in determining a team's moves than any other sport, because players do not have long careers. The entire starting offensive line (besides Lane Johnson) and Darren Sproles have already reached their late twenties and early thirties in age, and in a couple of years, LeSean McCoy, Jeremy Maclin, and Riley Cooper will be reaching their peak in age too. Chip Kelly does not have time to trade up for Marcus Mariota or Jameis Winston, and wait for them to develop. Not only is time a factor, but what the Eagles would have to give up to get either of those two would not give them a bang for their buck. The Eagles would have to trade multiple high-value future draft picks for Mariota or Winston, and then by the time they develop, they are going to need those picks they traded away to replace the current veterans who are reaching the end of their careers. When that happens, the last years Kelly will have with his high level players will be wasted waiting for a quarterback to develop, and then his best years with his quarterback are going to be wasted waiting for the rest of the team to develop. This potential problem can be solved by simply trusting Nick Foles.

Yong Kim/Philly.com

The general misconception about Chip Kelly's offense is the need for a mobile quarterback. While having a mobile quarterback helps Kelly's cause, he does not have to have one. If he did, Nick Foles would not have gone 14-4 in the offense, nor would he have been as productive as he was. Chip Kelly needs a quarterback who can make efficient decisions and keep up with the tempo he wants the offense to run at. Nick Foles can do just that. Foles has shown a slight injury prone in his time in the NFL thus far, which has to change if he wants to be the franchise quarterback for the Eagles. Along with his injury issues, Foles has to clean up the back-foot throws that increased his rate of interceptions this year. Taking care of the football is what set Foles a part as the potential franchise quarterback in 2013, and if he returns to the 2013 Foles in terms of taking care of the football (of course, the 27-2 touchdown-to-interception will never happen again), he will cement himself as the Eagles' guy, and Chip Kelly will have to accept it.

Now that the quarterback situation is resolved, Chip Kelly can focus his attention on the glaring problems that will prevent his football team from winning if the future in they are not addressed. Those problems of course, revolve around the Eagles' defense. The Eagles cannot give up an average of 375.6 yards and 25.0 points per game again in 2015 and expect to contend with the elite NFC teams. Chip Kelly and defensive coordinator Bill Davis have to fix the defense, starting with the secondary. Teams began picking on Bradley Fletcher at the end of the season, and at times, it got tough to look. Of course, Kelly and Davis did not help Fletcher's cause by leaving him on an island against top NFL receivers, but still, Fletcher was not even putting up a fight. Along with Fletcher is Cary Williams, and while Williams is physical and can hold his own when he covers tall receivers, he commits too may dumb penalties that kill the Eagles. In other words, cornerback is a clear hole for the Eagles that needs to be filled.

Another questionable player on the Eagles’ defense is safety Nate Allen. There are times where Allen looks like a competent NFL safety, and there are others where he simply looks lost on the field. If he has solid corners in front of him, he along with Malcolm Jenkins could potentially make a solid safety duo. But the fact that Allen relies on the corners in front of him to play well and struggles with consistency on a play-by-play basis, shows that he is replaceable.

The Eagles fate at outside linebacker will be determined by Brandon Graham’s decision to stay in Philadelphia or walk, along with the development of 2014’s first-round pick in Marcus Smith, who could not get on the field at all for Philadelphia this season. Trent Cole is getting old, and only has a few years at most left in the tank before he decides to call it a career. Brandon Graham showed signs of possibly being a legit outside linebacker, the problem was, he barely got on the field because of Trent Cole. Playing time alone has caused Graham to think about walking away from Philadelphia, and if does, outside linebacker all of a sudden becomes yet another hole for the Eagles to fill on defense.

Owner Jeffrey Lurie, general manager Howie Roseman, and head coach Chip Kelly have an array of decisions to make these next few months leading up to the draft and including the draft itself. If the Eagles fill the necessary holes on defense through the draft or costless agency, and stabilize the offense with Nick Foles at quarterback, they will be in a good position to return to the playoffs once again in 2015. Whether or not the Philadelphia Eagles will be good enough to contend for a Super Bowl, well that remains to be seen.