The Philadelphia Eagles had one of the better defenses in the NFL last season, recording a league-high 50 sacks in large part to solid play from their defensive line. They'll likely need that sort of play out of the front four again this season, too -- but it probably won't be evident when the preseason gets underway.
The injury bug has bitten the Eagles' defensive line quite hard, it seems, as all four starters will likely miss Philadelphia's preseason opener. SB Nation Philly has a nice summary of what exactly is ailing each of the front four:
On Wednesday, the Eagles sent Cullen Jenkins for an MRI after the defensive tackle left practice with hamstring troubles. Trent Cole has not seen the field since injuring his AC joint on Monday. Jason Babin is out for 2-3 weeks with a calf strain, and Mike Patterson is still recovering from surgery to straighten out the blood vessels in his head.
The Eagles are hoping if they rest their obviously ailing defensive line during the preseasons, these injuries will be more unlikely to linger too far into the regular season. Hopefully, for their sake, they're right.