Guys get hard hits on the ball all the time in the league. I understand it was a good hit, but I guarantee you Kubiak doesn't accept that as an excuse for him fumbling. And I just found the quote right after I typed that.
Kubiak on Martin: “There’s no excuse for those fumbles. We don’t accept that. He’s going to play a lot. We like him and we’re going to trust him. So he can’t turn it over.”