I don't think it is that simple...
There are definitely other variables at work. I use the Eagles too and have played every game so far and am at wk 10.
I'm one of the worst teams in the league when it comes to sacks (bottom 5); although I've started to get more over the last few weeks. I'm a top 5 rush D, and middle of the pack secondary in terms of yards given up, but in the top 5 in take-aways (INTs): Samuel 5, Sheppard 4, Brown 3, Bradley 3, and Hanson 1.
The most yards I've given up was 347 in wk 1 (against the Rams). I didn't get one sack, and might have sneezed on the QB once. Holt and Drew Bennett torched me...why...because the QB had ALL DAY.
Even if your corner is a 99 you cannot expect him to keep up w/ the WR the whole time, and if you are not getting a pass rush then your secondary is definitely going to struggle no matter who you have out there.
Thru wk 9 here's my sack total:
Clemons 3
Parker 4
Cole 1
Gaither 3
Julius Peppers has 9 sacks already...2 less than my entire team.
Philly is good against the run, and they have ballhawks in the secondary but w/ no pass rush they WILL get burned.
I'm also using the Raiders in my 'chise and was able to hold the Jets under 150 yards passing and Derrick Burgess, a DE better than anyone on Philly, posted 3 sacks in that game alone...I had a total of 5. In one game w/ OAK I had more sacks than I did thru 5 weeks w/ Philly.
Then look at Phillys LB Corps...Below avg in comparison to the rest of the league. While good at stopping the run, and possessing decent coverage ratings, they have below avg pass rushing ratings and MAN COVERAGE ratings...and Philly's interior linemen are run stoppers...There not Albert Haynesworth or Warren Sapp, a sacking DT.
Your pass rush and man coverage work hand in hand, and if you aren't getting sacks then expect your secondary to feel the repercussions of that.