I agree with you, this is a bad deal for ya. Upgrade at QB isn't worth the cost at WR.
I'm not too fond of DJax, as he is very big-play dependent. If you could sell him on the big-play ability of DJax and tell him that he isn't getting the second best WR for a slight bump at QB, I'd like that better (So the deal would be the same but switch him with Welker) Or if he would take it, add in Holmes and ask for either D. Baldwin or K. Wright. Wright could be great to start the year with Britt out, then you could flip him for a more long-term player when his stock is very high. And I just like Baldwin (shouldn't let emotions get involved, but he was a solid WW pickup for me in a few weeks last year)
Looking at your overall roster, who are some of the options left on WW? Name top 4 or so best WR/RBs. You have 1 stud RB, 1 (potentially) solid "FLEX" guy, a guy holding out (very dangerous if you remember last year), a handcuff to a guy you don't have (Ronine Brown), and a guy in Washington. Then at WR you have 1 stud, a "big play" guy, an unhappy guy on an abysmal offense with atrocious QBs (Holmes), and then Moore.