Based on your post it seems that you are assuming that because they didn't (or couldn't) get a first round pick for Jimmy yesterday that they couldn't get a first round pick during the offseason. I think that's a terrible assumption.
Jimmy G's value was greatest right before the draft b/c.....
1.) He looked great in his latest game action.
2.) He would have the full offseason (including training camp) to acclimate to his new team (for chemistry purposes).
3.) It would give management plenty of time to analyze if they want invest in his future (whether by franchise tag or long term contract).
Instead, what has since happened is...........
1.) Jimmy didn't look good in camp.
2.) The team will only be getting him for half the season.
3.) Teams that may have been the most interested may have gone in different directions for their QB plans.
So yes, I think his market value and trade power has gone down and that it's not wise to assume that what they got yesterday is the best they could have got during the offseason.