What we know about the Eagles defense is based on the 16-game sample of Juan Castillo in 2011 and then a very uneven four games in the preseason. There was some good, some not as good and some downright question marks based on the study, and as the team moves into position to launch into Cleveland for the 2012 season opener, well, the defense is front and center of the spotlight.

As in, how good can this defense be?

I don't put a lot of stock, frankly, in the preseason. The scheme isn't complete, the veterans aren't amped to play and the games don't count in the standings. Thus, what you see in the preseason is very often not what you get in the regular season.

So we're going to view this defense as a brand-new toy, and Castillo gets to take the wrapper off on Sunday afternoon at Cleveland Browns Stadium. He has some new faces to work into the starting lineup -- DeMeco Ryans at middle linebacker, Mychal Kendricks at SAM linebacker, Brandon Boykin at slot cornerback and Fletcher Cox at tackle (when the Eagles open with Cullen Jenkins at left end in their "heavy" package).

The evolution of the defense last year was interesting to watch. The Eagles were thrown together so quickly, and Castillo learned on the go. The early results were inconsistent. There were times when the Eagles played fast, physical football and dominated the line of scrimmage. There were times when the communication failed and large gaps in the defense appeared and the tackling was poor and the defense allowed huge plays.

By the end of the season, the defense was terrific. In those last four games ... you know the numbers. You know the spin. You know the results.

It's all new now. The slate is wiped clean. What does Castillo do in Year 2 with an extremely talented group? How aggressive is the scheme going to be? How will he adjust when teams look to defuse the pass rush with screens and quick hitters and draws and mis-direction plays? How does Castillo win the battle in the fourth quarter?

As much as the onus is on the talent here, some of it very young, it is also on Castillo. He showed last year how hard he is willing to work and how that hard work translates into improvement, as the final four games indicated. He comes into the 2012 season in an entirely different place than he was a year ago from an experience standpoint.

Castillo, see, has walked this path before, and no matter how much confidence he took into last season, he had never been in that position. He had never been in the heat of the fourth quarter of a regular-season game, nor had he taken a group of 11 players and worked them to fit as one.

The stakes this season are high, of course. They always are. Ryans was acquired to fill a huge need at middle linebacker as an emotional heart of this defense. Kendricks was drafted to step right in at SAM linebacker, and he played well in the preseason. Boykin replaces the veteran Joselio Hanson, now in Oakland. Cox made huge strides in the preseason and is one of the many outstanding players along this defensive line.

What do you expect if you're Castillo? Cleveland opened the preseason game a couple of weeks ago with a safe sideline pass to rookie wide receiver Josh Gordon, who was covered well by cornerback Nnamdi Asomugha. The pass was complete. The first dive was a good one for Cleveland until tackle Derek Landri broke up the party with a sack of quarterback Brandon Weeden and forced a turnover.

After that, the Eagles went after Weeden and got to him a lot. The Browns didn't do much of anything else offensively.

This time, you would expect, Cleveland will be very prepared for the pressure-based scheme of the Eagles defense. With that, though, the Browns have a rookie a quarterback, a rookie (Trent Richardson, if he's healthy) at halfback, and a couple of rookies at wide receiver who are heavily part of the mix.

The Eagles, on paper, have a lot of advantages on the young Browns offense. The games, as we know, aren't played on paper.

So we're going to find out about Castillo and his defense and how much those final four games from 2011 meant for 2012. We're going to find out about the defense, straight away. Right now, we know bits and pieces. Starting Sunday, we find out every nook and cranny and strength and weakness, with a season riding on the outcome.