The Jets have had a ton of injuries at WR. Edwards obviously knows the system. This, at the very least, is a team signing a street FA that is familiar with their offensive system, and can contribute right away. Similar to NE signing Branch again; they needed a body that knows the system.
The other more in depth speculation could be correct, but I think that's the major factor.
If Rice can't go, we need to run more 2 TE sets with McCoy and Miller, and just run and pass out of the same formation. We really want to screw up Buffalo, start out with the 2 TE sets and run no huddle.