It's going to be a tough fight for both guys. Hughes will struggle with the striking and takedown defense of Penn, then once he gets it down he has to worry about the guard of Penn. Penn will have to worry about the wrestling and sheer physicality of Hughes wearing on him. Ya know, the same dynamic of the last fight. We saw how that went.

And yes, BJ injured his rib taking Hughes back from the octopus guard. It's something to think about sure, but it's also something that could happen again. If he's on his back Penn is going to have create something in order to be able to get up and it might require amounts of core strength that he does not possess.