You are getting an upgrade to WR and QB, just like you said. Let's look at what you're giving away:
A Hernandez: battled injury all year, and doesn't have as good of production when Gronk is out (probably the remainder of the fantasy year)
Dez has been stepping it up lately. This will be a loss, but you're getting Decker who's way more reliable and productive over the season.
Andy Luck has a pretty favorable schedule from here on out, but so does MAtt Ryan.
Sounds like a great trade to me. If I were in your shoes, I would do it.
Standard Format: Aaron Rodgers, Josh Freeman; Doug Martin, Jamaal Charles, Maurice Jones-Drew, Vick Ballard, Pierre Thomas; AJ Green, Demaryius Thomas, Eric Decker, Stevie Johnson; Jason Witten, Vernon Davis; Stephen Gostkowski; Chicago