GGG wanted Canelo in September and Canelo ducked him, he then signed to fight Eubank jr., and he ducked GGG, so I'm ok with him fighting Brook at this point. It won't be an impressive win to me, since Brook is a much smaller man, but I don't blame him for fighting an opponent with name recognition. As others have stated, all dominant middleweight champs have defended against Welters: Hop, Hagler, Monzon, Robinson, Lamotta, Emile...etc. I would like to see GGG crush Jacobs and Canelo, but after that, there are no real threats to him.