The Dallas Cowboys had an awful defense last year under Matt Eberflus. And though the team is only one game into the 2026 season, it's not a stretch to say that the Cowboys defense looked even worse under new defensive coordinator Christian Parker in his debut.The Cowboys dropped their season opener to the New York Giants at MetLife Stadium on Sunday night in a 28-20 loss, and fans would likely argue that the game wasn't even that close.The Giants gashed Parker's new-look defense the entire evening. As bad as the film is, the stats show it was even more nightmarish than fans realize.Cowboys Defense Had One of NFL's Worst Games Since Week 1 of 2025New York Giants quarterback Jaxson Dart (6) scrambles with the ball defended by Dallas Cowboys safety Jalen Thompson (34) during the first quarter at MetLife Stadium. | IMAGN IMAGES via Reuters ConnectDallas' defensive production against New York wasn't just the worst in the NFL in Week 1 -- it was one of the worst in the league since the beginning of last season. Against the Giants, the Cowboys defense ranked 571 among 574 total defensive performances since Week 1 of 2025 based on estimated points allowed per drive, according to The Ringer's Sheil Kapadia.The Dallas defense had one game that ranked worse under Eberflus last season.On top of that, the Giants went 4 of 4 in the red zone on Sunday night and had the highest third-down conversion rate in the league, pending what happens on Monday Night Football between the Kansas City Chiefs and Denver Broncos.There's Simply No Excuses for the Cowboys New York Giants wide receiver Malachi Fields (88) carries the ball defended by Dallas Cowboys linebacker Dee Winters (53) during the second quarter at MetLife Stadium. | IMAGN IMAGES via Reuters ConnectCoaching aside, the Cowboys simply have too much talent on defense to have the kind of performance they did against the Giants. Dallas has some elite players on the defensive line in Quinnen Williams, Donovan Ezeiruaku, Kenny Clark and Rashan Gary, along with former All-Pro cornerback DaRon Bland in the secondary. That's not to mention the addition of rookie safety Caleb Downs, who had one of the best plays for the Dallas defense on Sunday night with an impressive strip-sack on Jaxson Dart.The good thing is, it can't get too much worse. After all, the Dallas offense didn't exactly do its part either in the first half, which could have covered up some of the miscues by Parker's unit. It's hard to imagine George Pickens dropping multiple passes in a game again this season and Dak Prescott finishing with just 175 passing yards.Still, Parker will need to figure things out fast. If the Cowboys repeat what happened in Week 1, they will likely fall to 0-2 with a home loss to the Washington Commanders. For Dallas fans, the season will already feel over before it really began if this ends up happening.—Sign up for the Cowboys Daily Digest newsletter for more free coverage from Dallas Cowboys on SI—Add us as a preferred source on GoogleFollow