What the hell are you guys talking about?
"Putting the straps" on Gronk means that he locked him down (supposedly). In other words, he didn't allow him to have a productive game.
I've read every single tweet on the matter, removed or otherwise--and NONE of them even come remotely close to mentioning his arm in any manner.
Sergio Brown acting like a douche is one thing, but I haven't seen anything to suggest that he was speaking of Gronkowski's past injury, let alone taking credit for it. Here are all of the deleted tweets:
http://blog.masslive.com/patriots/2014/11/sergio_brown_goes_on_twitter_r.html