Hopkins got hurt early on. That's what happens to these guys who fight Golovkin and Kovalev, they feel the power early and go into survival mode. Turns out, Hopkins is pretty good at the survival stuff.
OK, let's try to look at this rationally: Why the **** would Hopkins try to intentionally lose to one of the hardest punchers in the sport, when beating him at nearly 50 would be an amazing accomplishment that would only add to his legacy? What would he have had to gain from throwing the fight?