The schedule ahead offers a few breaks with games against the Bears, Dolphins and Redskins, but over the next four games, with a bye in between, the Eagles also need to face the Bills in Buffalo and both the Patriots and Seahawks at home.Both the numbers and the eye test suggest the Eagles’ defense isn’t just disappointing in 2019 — it’s just plain bad and getting worse. They might be able to sneak back to 9-7 with offense, but in a loaded NFC, that won’t make the cut for a playoff berth.Consider the Eagles’ season ruined, and they should be ruing their defensive mess above all else. The Eagles’ slow starts. Doug Pederson’s silly guarantees. Carson Wentz’s efficiency struggles. DeSean Jackson’s abdomen injury. Zach Ertz’s diminished role. The running game’s general ineffectiveness. The offensive line’s gross underachieving. The locker room’s rumored dissension. The team’s fading chemistry. Heck, Sporting News’ has even laid out some of these overall fundamental problems, not just once when the Eagles were 1-2, but once again going into the Cowboys game.But none of the above really matters, because it’s the defense continuing to dash all hopes and dreams of returning the team to that Philly Special glory of Super Bowl 52. Even more troubling is the fact that the defense also was largely responsible for the Eagles falling from 13-3 NFL champions to a 9-7 NFC wild-card team last season.WATCH: How Dak Prescott roasted Eagles on SNFBelow we deconstruct the latest defensive debacle with a detailed look at the seven biggest reasons for it.The Eagles are simply allowing too many points.After giving up 38 points to Vikings and 37 points to the Cowboys in back-to-back weeks, the Eagles’ scoring defense is down to No. 24 in the NFL at 26.6 points allowed per game, tied with the winless Bengals. They keep digging big holes by spotting teams big leads; according to Sharp Football, the 2019 Eagles are the first team to allow 20 or more first-half points in five games since the 2002 Bengals.The Eagles are the only team in the NFL to allow 20+ points in the first half in 5 games.First half points allowed by the Eagles defense, by week:Week 1: 20Week 2: 10Week 3: 20Week 4: 20Week 5: 0*Week 6: 24Week 7: 27*vs Luke Falk— Warren Sharp (@SharpFootball) October 21, 2019In that Week 5 game against the Jets, the Eagles allowed only six points to a Sam Darnold-less team down to its third-string quarterback. Take that outlier away, and the Eagles have given up 30 points per game.The Eagles are not getting to the quarterback.The Eagles have 17 sacks. That’s a relatively low number, and it’s also inflated by the Jets game, in which they had 10 sacks combined against Luke Falk and David Fales. Another three came Sunday night against Dak Prescott and the Cowboys, and that burst in pressure didn’t have any impact on the final outcome.It’s not like the Eagles don’t have talent up front. They’ve invested plenty in ends Brandon Graham and Derek Barnett, and especially in tackle Fletcher Cox, to help them put heat on the pocket with only four so they can consistently drop back seven.Because of that deficiency, defensive coordinator Jim Schwartz has tended to blitz more than usual to generate some kind of pressure. Of course, that doesn’t work when the team has cornerbacks who keep getting roasted one-on-one.The Eagles’ secondary somehow has gotten worse.The Eagles entered Sunday’s game optimistic with the starting cornerback combination of Ronald Darby and Jalen Mills back healthy. But they didn’t help much at all against Prescott, because the problem runs deeper than the perimeter, and the burying of ineffective Sidney Jones on the depth chart was meaningless. Avonte Maddox remains out, and Rasul Douglas, Craig James and Orlando Scandrick don’t scare anyone in coverage.Starting safeties Malcolm Jenkins and Rodney McLeod are showing diminishing skills with age, and backups Rudy Ford and Andrew Sendejo have provided no support. The Eagles are basically scrambling to find bodies who can make plays and not get burned outside-in.The lack of pass rush from players who aren’t blitzing from the secondary also has put a group limited on talent in bad positions. No wonder they were so desperate to trade for Jalen Ramsey before the Rams made the better offer. What’s most to blame for the Eagles falling to 3-4 after Week 7 for a second straight season? In one word, defense.After Sunday night’s listless, 37-10 loss to the NFC East-leading Cowboys in Dallas, fingers are being pointed, and a few notable pundits are screaming from just about every direction toward Philadelphia during the NFL’s typical weekly hot-take circus. The Eagles’ linebacker corps is slow and doesn’t recover well.They were without middle linebacker Nigel Bradham against the Cowboys, and earlier in the season, they were without outside linebacker Kamu Grugier-Hill. It’s also clear the Eagles made a mistake by not re-signing Jordan Hicks, who has been balling out for the Cardinals. Nathan Gerry is an active tackler, but he is often out of position and caught chasing.While all the focus has been on how bad the Eagles are on the back end, when these linebackers aren’t filling downhill against the run, the entire defense suffers.The Eagles have a bottom-half red zone defense.The Eagles’ red zone defense ranks 18th in the league, allowing teams to score touchdowns at a 56 percent clip inside the 20. But in the past three games, that’s up to 70 percent, mainly with the way the Vikings and Cowboys finished drives with balanced attacks.So on top of giving up long scores downfield, they also aren’t positioned to bend without breaking in the shadow of their own end zone.NFL POWER RANKINGS:Eagles’ slide continues into Week 8The Eagles are forced to compromise their run defense.Going into Dallas, Philadelphia could at least hang its helmet on stuffing teams in the power running game. But the Eagles had to soften up their coverage against the Cowboys so they weren’t burned downfield by Prescott and big-play wideouts.That whack-a-mole attempt opened huge lanes for Ezekiel Elliott, and the Eagles also couldn’t handle the changes of pace from Prescott, Tony Pollard and Tavon Austin running the ball. So while the Eagles succeeded in taking away the back-breaking shot plays, they traded for a more painful slow bleed.The Eagles have no easy defensive answers in sight.The biggest game-changing pieces at corner, Ramsey and Marcus Peters, were traded to other teams, and the Cardinals are not likely to deal Patrick Peterson. The combination of Schwartz’s shaky scheming and the team’s glaring personnel weaknesses suddenly can’t be fixed no matter how many more defenders the Eagles bench.