For GGG, Kessler's inactivity no longer makes him the threat I used to think he's be, but I'll say right now that Abraham, stylistically would be a nightmare for him - because AA's guard is purpose built to deal with a fighter who comes forward throwing two handed combinations. GGG doesn't get low, doesn't change levels, doesn't move his head inside a great deal and doesn't fight long. You need three of those things to beat AA.