Trying to build offensive juggernauts to win the Super Bowl is all the rage... until the next time a Super Bowl is won by a dominant defensive team, and then (almost) everyone will go back to copying that approach to building a winner. The consistently good teams - the Patriots and Steelers for example - play whatever style works to their strengths at any given time, and don't worry so much about what everyone else is doing. That's why I think that SackExchange and cheaterhater nailed it with their posts above.
And you know what? There were some very promising signs from the Jets' defense last year. I think they frequently wore down in the 4th quarter, perhaps due to lack of depth, perhaps to being on the field too much, most likely a combination of both. But they often kept the Jets in games against significantly more talented opponents, and they consistently played hard, and made good in-game adjustments. I think Bowles deserves credit for all of that, and earned more time to keep building this thing. And I am a guy that went into last season very skeptical of Bowles and feeling sure that he would be done after last season. Now, I think the Jets might be an edge rusher or two and a shutdown corner away from being a pretty dominant defense. There are also a bunch of really smart people very high on Jeremy Bates as OC, and especially in concert with Rick Dennison being brought in for the OL and running game. Now, if we can only get us a long-term QB!