I thought it had unofficially been mentioned that one reason for away fans being in the pop side was a police reason. After a review police were concerned with fans mixing on hardcastle. Having fans come out at the back of the pop side allows police to control the flow.

In addition I believe you can use seats used for
segregation towards numbers so there's an extra 100 or so on the the 800-900 away ticket sales and I believe as we give tickets to away officials in the main stand they can also be used (so let's say another 100 or so) add all that up and it makes roughly 1100 which I would argue is the amount required for the 10percent away allocation.