Standing Room Only at Alex Box?

I've seen people with blankets spread out near the poles on the concourse directly behind homeplate before and assumed they put them there to sit on. We've always had bleacher seats down one of the baselines so we didn't know for sure. For Saturday's game against Bama (Ben McDonald Day) though, we had SRO tickets and my gf decided to sit on the edge near a pole towards the end of the game (no one was around that area as it was the very last pole under the overhang on the concourse on the third base side) and an usher told her to stand bc sitting was not allowed . Like I said, this wasn't in a walkway or anything. I looked in the fan guide, but I didn't see anything listed about it (designated areas for standing, etc) unless I overlooked it. I guess you have to stand if you pay for standing room only? lol