It’s pretty hard to assess the Jets’ performance in their 30-21 loss to the Patriots yesterday without a firmer sense of how good (or bad) New England’s defense really is.

If it’s as awful as it played in the first few games of the season, so is this loss. Though Nick Mangold’s return helped the Jets’ offense look a hell of a lot better than it did last week against the Ravens, Gang Green still couldn’t sustain many long drives and managed only 97 yards on the ground. Bill Belichick and the Patriots countered the Jets’ attention to stopping their passing game by letting BenJarvus Green-Ellis run wild, and the Jets didn’t appear apt to adjust in turn.

If the Patriots’ defense is actually closer to that team’s normal (excellent) standards, then the Jets’ loss Sunday is not all bad. Mark Sanchez, afforded a bit more time to throw the ball, played well in spite of some butter-fingered (and allegedly mutinous) receivers. Shonn Greene flashed some of the bruising ability he hasn’t shown much of in almost two years. And the Jets’ defense, for better or worse, managed to rough up Tom Brady a bit.

Maybe I’m being a bit too optimistic, but this didn’t feel like a game that belongs in the same category as the losses in Oakland and Baltimore. It seemed more like the type of football game that could have easily gone the other way had a few close calls fallen in favor of the Jets: If Deion Branch had lifted his knee off the ground before being touched on the would-be fumble, for instance, or had Plaxico Burress’ toe landed an inch short of the sideline instead of an inch over it.

But they didn’t, so the Jets sit below .500, with critics beating their chests and hooting with glee.

And again: If the Patriots’ defense is actually terrible, this game could forebode an awful season for our blustering heroes. I strongly suspect that it isn’t.

Also: Seems pretty clear that opposing offensive coordinators are going to try to exploit Eric Smith’s lack of speed. Smith can tackle anybody, but he’s vulnerable in coverage. Of course, he’s hardly the only guy to fault in the loss.

But Mark Sanchez is the reason the Jets lost to the Ravens, 34-17. He was really dreadful, with three of his four turnovers returned for touchdowns and the other setting up a field goal.

– Gary Myers, N.Y. Daily News.

Sanchez did not play well. That’s true. He fumbled twice and made the terrible, desperate decision to try to force the ball to Santonio Holmes on what wound up a coffin-nailing interception and touchdown by Lardarius Webb.

But there’s just no way “Sanchez is the reason the Jets lost to the Ravens.” His gaffes all came thanks to awful, awful play from his offensive line. It’s easy to point the blame at the handsome, GQ-model of a quarterback when everything goes wrong, in part because no one was expecting much from Colin Baxter, Wayne Hunter and the Jets’ battered offensive line.

Think about it this way, though: If Sanchez and Joe Flacco changed places yesterday, and Sanchez helmed the Ravens’ offense instead of the Jets’ “offense,” which team would have come out on top? The Ravens, of course. Flacco made his share of bad throws and poor decisions, but had way more time with which to make them. Plus, the Jets’ inability to run the ball inside forced them to throw, which combined with their struggle to slow the Ravens’ pass rush to leave Sanchez looking like a three-legged (but still handsome) deer limping in Haloti Ngata’s crosshairs.

The Ravens have a strong defensive front, no doubt, and a series of schemes that confounded the Jets’ linemen. But none of the Jets’ front five — not even the usually great D’Brickashaw Ferguson — adjusted well enough to keep Sanchez from getting crushed on almost every passing play. And now that the line has been exposed as a glaring weakness, every defensive coordinator in the NFL should be thumping his chest over the opportunity to showcase his front seven and bolster his resume.

The small, personal upside to this is that it seems to have drawn into public consciousness the importance of center Nick Mangold to the Jets’ offense. As a former center, I’ve been barking Maddenisms for years about the value of a great blocker and strong communicator in the middle of a line only to be drowned out fantasy-guru types shouting about this quarterback’s arm strength and that runningback’s elusiveness. Truth is, if your line sucks so does your offense. That’s the story for the Jets right now.

Until Mangold gets healthy or the rest of the line makes some major improvements, Mark Sanchez will continue looking frightened and awful. Then when Mangold returns and the line play improves, we’ll hear all about the Sanchise Redemption and the Return of the Poise. And that will be welcome, because no one should look that bad on the field and this good off of it:

It seems like some in the media and blogosphere want to partly exonerate Antonio Cromartie for his brutal performance in the Jets’ 34-24 loss to the Raiders yesterday. I do not. Sure, at least one of his four penalties was probably a bad call, but most of them weren’t.

Cromartie finished second on the team with five tackles, but that’s generally a bad sign for cornerbacks. Darrelle Revis, for example, finished without a tackle. With Revis playing his typical dominant coverage, the Raiders obviously targeted Cromartie from the start — so much so that it became easy to forget Revis was even playing for long stretches of the game.

But worst of all, Cromartie followed a strong special-teams performance against the Jaguars with a backbreaking boot and bobble of a kickoff that led to the Raiders’ second touchdown in about a minute, a massive momentum shift that doomed Gang Green.

Not long later, Cromartie added injury to ineffectiveness, hobbling into the locker room with what is supposedly a bruised lung.

The Jets’ offense managed 24 points, impressive considering the sad state of their offensive line. Rookie center Colin Baxter played a hell of a lot better than he did against Jacksonville, but was physically overmatched by the Raiders’ strong defensive line on multiple plays.

It didn’t help that the rest of the Jets’ offensive line struggled, missing blocks and blowing assignments. The Raiders sacked Mark Sanchez four times. Most of the Jets’ best plays came on roll-out passes and runs outside the tackles, away from the overwhelmed interior linemen.

Sanchez had a good day, considering the constant pressure from the Raiders’ defense. But his lone interception came on an awful decision, throwing on the run to a multiply covered Derrick Mason in the end zone on a broken first-down play.