I agree with you on the facts that the Jags D is banged up and they are inconsistent, although at home they have shutout the Steelers and the Jets, and allowed Dallas to only score 17. That is 17 points allowed in 3 home games. The next five games they play are the Titans (at home), the Texans (at home), the Giants (MNF at home), Buffalo (away), and Miami (away). The Jags have a deep roster, especially on defense. I would hang on to them.
I would flat out reject it because I don't think he has a player (or 2) that he would be willing to give up that can help your team. Maybe he will come back with a better offer.