Let's be honest, Braun has cooled off because he's been exposed. He can't cut long promos or work long singles matches, so there was always a limit to what could be done with him. Getting as hot as he did led to him being put in a position he wasn't ready for and made his limitations all the more apparent. And he can't do the strongman spots that got him over because he's been constantly injured. Pretty much every freakishly large guy's body turns on him eventually, and Braun being in so many gimmick matches has probably accelerated that process.