Bad O-line. Bad QB. Only two legit weapons on offense; both on the decline. Bad secondary. Horrible give/takeaway ratio. Can't create turnovers. Can't sack or hurry the QB.
They're good in one facet of the game - run defense. In a league that's become all about the passing attack.

You claim the Jets O-Line isn't bad and cite that they are tied for 22nd in the league in sacks given up as evidence yet the first team you name as a bad O-line is the Bears... who are tied with the Jets at 22nd in the league for sacks given up. (The Giants, who you say are worse, are tied for the 2nd fewest sacks given up)

Forte's been fine but when you invest in a big name back, you'd hope to see improvement in the run game; it's been stagnant.

The defense carried the team last year and can't do it this year because the secondary took a big step back.

Looking at their schedule, the Rams is really the only bad loss. Last night was an ugly loss but not a game they were expected to win. And the Ravens is a quality win.