And there are two good reasons why.
First off, both Gruden's Buccaneers and Shanahan's Broncos collapsed in December, losing what seemed like sure playoff bids.
The Jets fired Eric Mangini because his team collapsed late in the season, blowing a playoff birth. Why would you want to hire a candidate to replace him who did the same exact thing?
Secondly, Gruden and Shanahan would want final say over personnel decisions. And after the myriad poor personnel decisions each made at their previous stop, why would the Jets want to give them that kind of power?