He had Happy feet early for no real reason. He had a pocket but because his first read wasn't there he was panicking. The first but sack on the first possession was 100% on him.
When Pitt started brining blitzes they were baiting him. They picked something up in film. Getting him to read the wrong hot route pre snap. Then having the pressure come from the other side.
They adjusted in the second half. It's hard to believe but ND only had 4 "real" possessions in the 2nd half. They scored TD's on two and drove to the Pitt 25 on the other before an interception.