Through two games, the Jets’ stat line on defense tells an ugly story. Zero sacks, zero interceptions and zero forced fumbles.

And, of course, zero wins.

It’s easy for an offense to avoid mistakes when the quarterback doesn’t feel any pressure, and that’s been the biggest problem for the Jets’ defense during their 0–2 start. Not only have the Jets not sacked the opposing quarterbacks, New England’s Tom Brady and Baltimore’s Kyle Boller, but they’ve rarely even come close to them, and NFL quarterbacks have an easy job when they have all day to pass. It’s one thing that in Week 1 the Jets made Brady look like the future Hall of Famer that he is. But it’s quite another that in Week 2 the Jets made Boller look like a star, which he certainly isn’t.

The Jets are the only team in the league that hasn’t forced a turnover yet and one of only two teams that haven’t recorded a sack. Boller and Brady have combined to complete 71.4% of their passes, with five touchdowns and a sky-high passer rating of 119.9. That points to problems both with coach Eric Mangini’s game plans, which have been too cautious and haven’t used enough blitzing, and with the Jets’ personnel, which is still more suited for the 4–3, Cover 2 defense that previous coach Herm Edwards ran than it is for the 3–4 defense that Mangini prefers.

There’s nothing inherent to Mangini’s defensive system that would prevent the Jets from putting pressure on opposing quarterbacks. Mangini is running essentially the same defense for the Jets that the Patriots employ, and New England linebacker Mike Vrabel leads the league in sacks through two games this season. Shawne Merriman, the San Diego Chargers linebacker who led the league in sacks last year, also plays in a 3-4 defense.

But the Jets don’t have the same type of personnel that the Patriots, Chargers, and most other 3–4 teams have on their rosters, and the failure to make strides toward getting that personnel is a major failing of Mangini and general manager Mike Tannenbaum. Most teams that run a 3–4 defense have a big defensive line anchored by a huge nose tackle whose job is to absorb double teams and free up space for the linebackers behind him. The Jets are trying to use Dewayne Robertson in that role, and he’s both too small to effectively play as a true 3–4 nose tackle, and too quick to have his abilities go to waste in a defense that asks him to absorb blocks rather than penetrate and make plays.

Robertson’s inability to play the standard nose tackle role also means the Jets’ most talented defensive player, inside linebacker Jonathan Vilma, isn’t able to get the most out of his talent. With bigger, more physical defensive linemen in front of him, Vilma would be able to come free on blitzes and wreak havoc in the other team’s backfield. In the Jets’ defense, he spends all game trying to battle offensive linemen and rarely makes plays. Mangini would be wise to move Vilma around more and let him rush the passer from the outside, where he might be able to use his speed to get around opposing offensive tackles.

Outside linebacker Bryan Thomas led the team with 8.5 sacks last year and is expected to be the Jets’ primary pass rusher again this year, but Thomas lacks the speed around the edge that elite pass rushing outside linebackers like Merriman have. Opposing teams can almost always count on their offensive tackles to beat Thomas one-on-one.

The biggest disappointment in the Jets’ pass defense is that safety Kerry Rhodes has done so little in the first two games. Last season, Rhodes was one of the league’s most versatile defensive playmakers, with five sacks, four interceptions, and three forced fumbles. This year, he has mostly stayed back in coverage and allowed the play to develop in front of him. To an extent, that has been by necessity — the Patriots were doing such a good job protecting Brady that Rhodes probably wouldn’t have accomplished much by blitzing. But against the Ravens, who were missing both starting quarterback Steve McNair and their best offensive lineman, Jonathan Ogden, Rhodes should have been roaming all over the field. He wasn’t.

The Jets have also had problems against the run. Although they haven’t given up any long runs and are allowing just 3.5 yards a carry, they’re not tough enough in short-yardage situations. The Jets have given up 18 rushing first downs, tied for the worst in the league, and their opponents are 9-for-9 at picking up the first down when running against the Jets with one yard to go.

All these problems add up to one big mess of a defense, which no one expected when the Jets hired their defensive wunderkind of a coach. Mangini’s first year was a success, and two weeks into the season is too early to call his second year a failure, but Mangini needs to make changes, and he needs to make them soon.

Mr. Smith is a writer for FootballOutsiders.com.