A lot of things go into playing good defense. You need the right combination of size and speed. You can have a big defense with okay speed or a fast defense with okay size. Either way, you need a bit of both. Defense also requires discipline and execution. Players have to fit within the scheme and do their job.

You can also make an argument for confidence, trust and attitude.

Think about the Ravens defense and how good it has been since the 1999. There have been a slew of different coordinators, coaches and even players. The scheme has changed from 4-3 to 3-4 to hybrid and everything in-between over the years. That defense will have the occasional down year, but is generally among the best in the league. One of the keys is that the group believes it will be outstanding. The players are confident and play accordingly. The defense also plays with a lot of attitude. This ties in to the confidence factor. They believe they will be good and that helps them to play aggressively. They attack. They play tough, physical football. That standard was set years ago, but the current team is still trying to live up to it.

The Eagles haven't had a top flight defense since 2008, which was Jim Johnson's final year. Since then the defense has been run by Sean McDermott, Juan Castillo, Todd Bowles and Bill Davis. Each coach had different beliefs than the guy before him. Beyond that, there have been no transcendent leaders to teach new and young players how to be great.

Trent Cole is tough as nails and has had a very good NFL career, but he's not the guy that calls 20 players together and fires them up. You need a leader for that. Someone that is a tone-setter. The Eagles do have guys like DeMeco Ryans and Malcolm Jenkins who can be like that. The problem is that Ryans has yet to be on a good Eagles defense and Jenkins is new to the team. These players don't have the track record that they can point to.

But maybe that is changing.

The Eagles played terrific defense for three quarters against the Rams. Then the Eagles shut the Giants out. The team notched 12 sacks in those games and came up with some big takeaways and critical stops. For most of those two games, the defense was outstanding.

Davis mentioned in his press conference that one of the big developments is players trusting each other. They are playing like a group, rather than 11 individuals who happen to be on the field at the same time. Teamwork is critical whether dealing with the run or the pass.

Run defense is based on gap integrity. A gap is a space between offensive linemen and/or the tight ends. Every gap must be accounted for. If players leave their gap to help someone else, the runner can cut back and then have space to work with. Players have to control their gap first and then work their way to the ball under control.

Pass defense requires the back seven to do something similar. If zone, the players have to get to their cover spot and control that area. If man coverage, the players must choose the correct receiver to cover and stick with that player. Receivers can still get open if the right play is called against a given defense, but the receiver should be somewhat covered and then tackled quickly to limit RAC yards.

The Eagles played with good discipline against the Giants. You didn't see big cutback lanes open. You didn't see receivers running around wide open. The defenders worked together by executing their individual assignments and trusting each other.

The defense also played with some attitude. From the moment that Connor Barwin first hit Eli Manning on the initial third down of the game, the defense really came alive. They expected to beat blockers and get to Manning. And that's exactly what they did, until the Giants finally pulled him and put Ryan Nassib into the game. Some of those sacks were coverage sacks. The members of the secondary helped the pass rush by covering well. And each hit on Manning sped up his internal clock, which meant the guys in the secondary had to cover for shorter times. That's great team defense.

And this is the kind of thing that can be repeated. That's the best part for me. That game wasn't about one player having a phenomenal night. No player on the defense had the game of his life. The unit played well overall. Barwin did have three sacks, but at least one was due to coverage. I didn't see him do anything that I think was a total fluke. I doubt Barwin gets three sacks again this year, but he can pressure the quarterback well in future games. If he can force errant throws that end up as incompletions or short passes that don't move the chains, those plays can be as good as a sack. The key is ending drives by pressuring the quarterback.

The Eagles are going to play with a lot of confidence when they take the field in Arizona this Sunday. I don't expect another shutout. I do expect the defense to play well. If the defense can limit Arizona to around 300 yards and 17 or fewer points, that will be a good game.

The defense had one really impressive game last year. They held the Bears to 257 yards and 11 points. The following week Kyle Orton and Dallas piled up more than 400 yards on offense and almost upset the Eagles. The one good game proved to be an anomaly. It is up to the players to make the shutout the beginning of something rather than just one great night.

I think that can happen. I know I want that to happen. I can't wait until Sunday to see if that does happen. It sure would be fun for the Eagles to once again have a good defense. The players got to experience defensive excellence the last time out. Let's hope that becomes the standard they try to play up to.