Hardy was marketed as a KO striker when he had a few KO's over nobodies. He did nothing to cement this reputation in the UFC with his single KO over a collapsed-lung one-dimensional striker in Markham.
I respect that he has spent a lot of time at 10th Planet filling out his skillset and he's not a bad fighter or anything, but his hype seems to me to be mostly about attracting UK fans to the UFC fold... not his actual potential.
So, just because the UFC marketed him as one doesn't mean he was one and even after he KO'd Markham he said in the interview with joe he said "No power aye" and then joe asked if thats what Markham was saying about him and Hardy said "to be honest it's not what i am known for but it was great to show case that i do have it". not exactly word for word but it was pretty similar.
And having a collapsed lung or not, it doesn't make a difference when you get punched square along the temple.