The Jets are "doing very well on defense" because of who they've played. Tampa (say no more), the Patriots (not Brady's finest hour, but that game was a windy, rainy mess), Buffalo (say no more, and Manuel still did ok), and Tennessee (say no more, and yet Locker/Fitzpatrick still threw for 250+ and 4 TDs). They've given up 7 passing TDs already and they haven't faced anyone the caliber of Ryan.
I've stated in several other threads that I do think Rivers will have a good game but I can't possibly see sitting Ryan, at home, for him.