Nick Foles has yet to throw an interception while going 4-1 in his five starts. (USATSI)

The Philadelphia Eagles are 31st in total defense and 31st in pass defense, numbers no unit wants to have on its résumé.

But that defense also hasn't given up more than 21 points in the past seven games, which is why the Eagles are surging and atop the NFC East. A month ago, the Eagles were 26th in points per game but have improved that to 15th in the league at 23.6 per game.

On the other side, the Eagles are taking better care of the ball. Nick Foles has not thrown an interception all season. The offense, which started out fast before fading some, is rolling again with Foles.

The Eagles are 6-5 as they head to their bye week, so what have been the keys to the turnaround?

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There are a lot of reasons on both sides of the ball. I will take a look at each side and show some of the things in pictures here that I think are impacting the Eagles' surge.

To be fair, the Eagles haven't exactly beaten up on top teams in the past three weeks. Philly beat Oakland (4-6), Green Bay (without Aaron Rodgers) and Washington (3-7). That isn't exactly a tough slate, but it outscored those opponents 100-49. That is impressive.

In the two weeks before that, the Eagles scored a total of 10 points in losses to Dallas and the Giants.

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So let's start with a look at Foles. He has started the past three games and has five starts total. The Eagles are 4-1 in those starts, and he has 16 touchdown passes this season with no interceptions. He has a passer rating of 128.0, which is tops in the league. But the number that impresses me aside from the 16-0 TD-Interception ratio is the 9.6 yards per attempt. That is also the best in the league and indicates he is hitting the big play.

Some of those big plays are by great design and execution. But others have come because Foles is patient in the pocket. He will wait for plays to develop down the field.

Here's a look at one of those, a 65-yard throw to Riley Cooper against the Raiders.

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As you can see by the pictures, Foles opens to the right and looks that way. That has the Raiders flowing that way. When Foles comes back to the middle, it appears he will go to tight end Brent Celek (red circle), but instead slides to his left and uncorks a big throw to Cooper, who is in man coverage. That's veteran-type patience and eye maneuvering to make the play work.

It helps that Foles has arguably the best offensive line in the league and has a dynamic back in LeSean McCoy who makes people miss and fits the spread offense perfectly. That line has had all five players start all 11 games, which is huge. The left side, where guard Evan Mathis and tackle Jason Peters play, might be the best side of any line in the league.

That line, which uses a lot of five-man protections because of the scheme, allows Foles to be patient. Foles has been sacked 12 times in his six games, but Michael Vick was dumped 18 times and some of that was on him. Routes that take time to develop can be completed because they do a good job with the five-man protection. Blitzes sometimes hurt the line, but here's a look at one of those long-developing plays that the line did a great job of protecting from last week's game with the Redskins.

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It's a third-and-11 play from the Eagles 11. They motion DeSean Jackson from the right side to the left side inside of Celek and Cooper. Jackson (yellow circle) runs a corner route, while Celek (blue circle) runs an out and Cooper (red circle) runs a dig. The play takes time to get Jackson to the open area, but the line, as you can see by the last picture, does a great job in protection. There isn't a body near Foles as he throws.

Here's a play that highlights the design aspect of Chip Kelly's offense and how he can scheme players into big plays.

The Eagles have a first-and-10 from the Washington 43. There are two receivers to the right and the Eagles motion McCoy out of the backfield to the right. Foles takes the snap in the shotgun and looks that way. The Redskins flow that way, but it's a screen back to Celek (red circle) on the other side. The play is designed so well that Mathis doesn't even have anybody to block when he gets out. Celek turns it into a 42-yard gain and is tackled just short of the end zone to set up a McCoy score.

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McCoy's ability to escape players in the backfield and be a threat in the passing game adds so much to the offense. He makes it all go. Here's a first-and-10 play where the Eagles schemed him up to be one-on-one with linebacker Ryan Kerrigan.

As you can see from the pictures, McCoy lines up in the backfield. The Eagles' two tight ends line up on the right. Both of those players take an outside release, and then run a route inside from right to left. That creates traffic and makes it hard for Kerrigan (red circle) to get out on McCoy. That's a bad matchup anyway, but the traffic helps McCoy get free down the sideline and Foles throws a nice pass for a 49-yard gain to set up a touchdown.

As you can see, there are a lot of reasons the offense has clicked the past three weeks. Foles is the biggest reason. He looks more and more comfortable each week. It would be hard imagining the Eagles sitting him down when Vick is ready to play.

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Defense

The biggest thing I noticed from the defense the past month is the improved play of the players up front. The Eagles rotate six down players in their 3-4 scheme and all are 25 or under. The two best are tackles Fletcher Cox and Cedric Thornton. Cox is an athletic freak who is coming off a dominant game against the Redskins. Thornton is an underrated player who can make big plays in the run game and get pressure on the quarterback. Rookie Bennie Logan, the nose tackle, also impressed against the Redskins.

It also helps that outside linebackers Trent Cole and Connor Barwin -- especially Barwin -- have played much better than they did early in the season.

Here's a look at some of the highlights from that group. The first is a run stop by Thornton.

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You can see Thornton lines up head-up with left guard Chris Chester. At the snap, he powers into Chester and stands him up. That's impressive enough, but when Alfred Morris takes the handoff, he is able to shed the block and make the tackle for a 2-yard gain. Later on that same drive, Thornton moves to a standing-up end spot on the left side and beats Tyler Polumbus around the edge to force Robert Griffin III to step up and into a sack by Cole.

Here's a play by Cox that shows how special he can be as a player.

As you can see, Cox (yellow circle) lines up standing up on the left side. At the snap, he makes a hard rush inside but reads screen. He turns and runs to his left and helps chase down Roy Helu from behind. If you watch the play, you will be amazed by his speed and quickness.

The Eagles also used creativity to get pressure in that game. Defensive coordinator Billy Davis did some interesting things up front and in the secondary. One of the sacks came off a nice stunt. Here's a look.

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The Redskins empty the backfield and spread out the Eagles. On the play, the Redskins have Pierre Garcon open on a shallow cross. One problem: linebacker Najee Goode loops around to dump Griffin before he can make the throw.

The Eagles slant Cox and Cole inside and that creates a space for Goode to loop around and drop RG3 just as he is ready to throw to Garcon on the cross.

The Eagles still have issues in the back end of their defense, but they are even improved there. They played down two starters on defense against the Redskins, and corner Roc Carmichael, a replacement starter, was picked on late. But they aren't nearly as bad as they were earlier this season.

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So as you can see, the Eagles are doing a lot of good things as they head to their bye week and prepare for their final five games. Those two lines are the keys to the success, but Foles' ability to play with calm and poise, with McCoy's greatness, are also big reasons why the Eagles are the favorites in the NFC East.

Things I saw on the tape

1. I am so glad that I put Bengals linebacker Vontaze Burfict on my midseason All-Pro team. He is having a heck of a season. Burfict made a great play on the scoop-and-score last week against the Browns when he diagnosed the screen, ran to the football, caused it to pop out and then picked it up and ran it in for the score. But he made a lot of other impressive plays in that game. He was all over the field. One of my favorites came in the first quarter when Cleveland had a first-and-goal at the 2.

Here's a look.

Burfict (yellow circle) lines up on the line on the right side of the defense, and knifes around to stop Willis McGahee for a 1-yard gain on the other side. I think McGahee scores there if Burfict doesn't come around and make that play. The Browns throw two incomplete passes the next two plays and settle for a field goal.

What also impressed me about Burfict from that game is how much better he was in coverage. He has trimmed his body down, and it shows in coverage. He is also much more aware now in zone drops. As an alum of Arizona State, where Burfict played, I watched all of his games. I never saw this type of play coming from him. I always thought he was talented and athletic, but inconsistent and wild. Credit the Bengals coaches -- defensive coordinator Mike Zimmer and linebackers coach Paul Guenther -- for getting this kid to play the way he's playing.

2. Watching San Francisco-New Orleans tape, I wanted to see how 49ers outside linebacker Aldon Smith did in his second game back after his stint in rehab. What I saw was a player who doesn't seem to have the same explosiveness he had last season. Smith was blocked in one-on-one situations a bunch and at times didn't get any push on left tackle Charles Brown. He had one hurry the entire game. He did seem to get more comfortable as the game moved along as he was spotted in and out, so maybe he will be getting back to his old ways down the stretch. Against the Saints, he didn't impress much.

3. The Seahawks played without Brandon Browner last week at corner. He is a good player. But I have to say that there isn't much of a drop-off with Walter Thurmond, who had a pick-six of Christian Ponder. Thurmond has been the team's nickel corner, so he has played a lot. But as a starter he did a nice job last week. Thurmond isn't as big as Browner, but he can play a physical style. His pick-six was a play he made with his head. On the play, he was lined up inside in what looked to be off-man against Jarius Wright, but was really a zone coverage. At the snap, he looked inside to Ponder and saw him eye-balling Cordarrelle Patterson outside. So he jumped underneath the route and picked it off for an easy score. Ponder had to do a better job there of influencing Thurmond.

4. In studying the Denver offensive line, which got rave reviews for the job it did against the Chiefs, I thought left tackle Chris Clark did a better job on Tamba Hali than Orlando Franklin did on Justin Houston. Clark, who stepped in when Ryan Clady went down, handled Hali in pass protection for the most part. Houston had the better day, even though Peyton Manning wasn't sacked. He got the ball out so fast that it made it almost impossible to hit him. Another quarterback might have been sacked two or three times. Another battle I wanted to study was Broncos center Manny Ramirez against Chiefs nose tackle Dontari Poe. I thought both had some wins in that battle, with Ramirez turning Poe on some runs and Poe holding the point on others. The next time these teams meet, it will be interesting to see how those tackles play when the noise is loud and a factor in Arrowhead.

5. If you wonder why things have gone bad for Matt Ryan in recent weeks, look at the offensive line. There is one player, left guard Justin Blalock, starting in the spot he was projected to be in when the season started. Center Peter Konz, who struggled big time, is now at right guard in place of Garrett Reynolds, who was downright awful. Joe Hawley started at center last week against Tampa Bay. Left tackle Lamar Holmes was expected to be in the mix at right tackle, but he's starting for Sam Baker. Right tackle Jeremy Trueblood was picked up off the street. Buccanneers tackle Gerald McCoy abused Konz last week to get three sacks. Ryan was pressured all day. It doesn't help that Ryan is also missing Julio Jones. This is just one of those seasons for the Falcons where you chalk it up to bad luck and move on. But they better address that offensive line in the spring. They will be a good team again in 2014 -- but that line needs upgrading.

Three and outs

Three college players who have caught my eye

1. Randy Gregory, DE, Nebraska: Wow, does this juco transfer have some explosive edge ability. He can be special.

2. Ifo Ekpre-Olomu, CB, Oregon: He is a terrific man-cover corner.

3. Telvin Smith, LB, Florida State: He isn't big, but he can run. That's what teams want in their linebackers now.

Three surprising stats

1. Ravens QB Joe Flacco, the supposed mad bomber, is averaging 6.55 yards per attempt, which is 22nd in the league.

2. The Bengals, Broncos and Lions all lead their divisions, but all three are negative-2 in the turnover ratio.

3. The Carolina Panthers are 22nd in total offense, but lead the league in third-down efficiency.