Just my opinion, but I think Baker got the nod ahead of Clark because he wins more physical battles than Clark does. Clark reads the passing lanes and anticipates play better, but Nathan is your man with a physical forward, like Jones. Clark often get's bossed by the physical forward. Nathan's more physical play was the order of the day. (although I do think he took that task a little too literally for one that in honestly should probably have been a PK (again, IMO).
If you think he was a liability yesterday, how many many fewer goals allowed would you have been happy with? (for the slow, and anyone who reads this in three weeks or more, we allowed zero) Even the chances they had, were not down to Nathan. He had an outstanding game. Frankly, I would have made him MOTM if he had not been lucky on the penalty shout.