Then it's his fault for being off balance, isn't it?
He's in a position where one of two players is going to win the header: Bailly, or an opposition player. It's hardly out of the realms of possibility to suggest it wasn't going to be Bailly who won it, and he utterly fails to prepare for that or react to it. Again, KDB does; he's ready to go and pounce on the opportunity as soon as the header is made. Why isn't Blind ready to react, or positioned in such a way where he will be able to adapt?
I'm not even saying it's all his fault: Bailly can take some culpability for not challenging the header, but the idea that the goal somehow wasn't Blind's fault at all when he fails to do
anything whatsoever is daft.