I do agree with smitty that I think this trade may be somewhat worth it if it accelerates the process of getting rid of Garrett and/or Dak as far as there being one less excuse for them in Jerry's mind. I definitely think part of the reason for the trade is to give Dak 1.5 years of Cooper in order to more accurately evaluate him.
Now, I'm not saying that trading for a WR like Cooper was necessary to evaluate Dak in the first place but if it accelerates that process in the front office's mind it may be worth it.