This is the fifth in a series analyzing the Eagles, position by position, leading into training camp ...

As they did last year, the Eagles made the line of scrimmage a huge focal point with the way they attacked the player-acquisition side of things in the off-season. This time, it was the defensive side of the ball that received the most attention. The Eagles used the trade route and the draft to hopefully provide greater depth and pass-rush punch for 2010 and beyond.

The defensive was already pretty darn good, featuring Pro Bowl right end Trent Cole, two very solid tackles in Mike Patterson and Brodrick Bunkley and solid veteran left end Juqua Parker. Depth, however, was a major problem. Chris Clemons never became the edge rusher the Eagles hoped he would become after they signed him as an unrestricted free agent, and Victor Abiamiri couldn't stay 100 percent healthy to add some pass rush from the inside positions when the team went to its nickel alignment. Veteran Darren Howard's productivity waned after a terrific 2008 campaign.

So the Eagles made the line a priority. Tempted to get into the bidding for the top unrestricted free agent, Julius Peppers, the Eagles instead saw him sign very quickly with Chicago. The remainder of the free-agent crop wasn't enticing, so the Eagles turned to the trade waters. They found a willing partner in Seattle, which was willing to take a chance on Clemons and give up Darryl Tapp. In Tapp, the Eagles saw a player whom they felt would flourish in this scheme with his up-the-field aggressiveness and his speed off the ball.

So the trade was made. And the defensive line transformation was underway.

Now, when September 12 rolls around and the Eagles play Green Bay at Lincoln Financial Field, the starting line may very well look the same. But as the game goes on, the Eagles would love to rotate the players on the line and use eight and even nine linemen over the course of the game. They expect Tapp to provide quality snaps at both left end and right end. They think first-round draft pick Brandon Graham -- still unsigned and with no update to report at this time -- can challenge Parker for some playing time. Third-round draft pick Daniel Te'o-Nesheim picked up things very quickly in the spring and looks like he has a chance to help as an inside pass rusher right away.

At tackle, the Eagles are excited at the way second-year man Antonio Dixon has developed in the off-season. He is certainly someone to watch closely. Dixon is a big man who has some quickness. He came to the Eagles as a raw project and gave some quality snaps last season. He is looking for more this time around.

Clearly, the Eagles hope for more of the same from Cole -- who had 12 1/2 sacks and made his second Pro Bowl last year -- and from Parker, who had a career-best eight quarterback sacks. They also hope that both Patterson and Bunkley hold the point of attack and play the run well, and that they can help with a push inside against the pass.

But the key to this defense is getting off the field on third downs, and that means improving the pass rush. The Eagles will tinker with their nickel alignment as they try to get four ends on the field at the same time. They need the rookies to contribute. They need Tapp to be a big-time pass rusher who plays with a ton of energy.

And they need the depth. Trevor Laws, a second-round draft pick in 2008, has to step up or he is in danger of not making the team. Laws looked stronger and quicker in the spring, for sure. He has worked hard to get his game back this year. Seventh-round pick Jeff Owens is a powerful young man who had a fine career at Auburn. Undrafted rookies like end Eric Moncur and tackle Boo Robinson have to open eyes every day in training camp.

The defense has its questions, no doubt about it, and fine play from the line will help answer those in a very positive manner. It all begins up front, and that is why the Eagles spent so many of their resources helping a good line hopefully become a great one.

Bottom line: If Tapp plays as well as the Eagles expect, and if the draft picks come to play, this line could be very, very good. If not, the Eagles will again look to Cole to be the down-in, down-out star of this group. Parker is a good player, but the Eagles need more than two players getting to the quarterback.

Next: Linebackers