Typhoon
Football is a difficult sport to unretire from. The only reason Jay Cutler came back was because his wife wanted the money. For $10 million for one year, who the hell could blame her. But he ended up paying for it physically, with several cracked ribs and a concussion. Gronk was a beast, and may still be very effective. But I agree with your thoughts about being away and coming back and getting injured.
Gronk coming back with Brady has the ingredients for a great story, but I don't see it materializing as such. Great move for Tampa Bay though. They're gonna make a lot of money this year with asses in the stadium seats. Not to mention team jersey sales.