There's a couple of rows in block 207 (I think) that no matter how full, are rarely occupied. As the seats are all together this suggests that someone with more money than sense who is only interested in taking people to the big games has them, or a tout/ reseller has them and is getting no takers at an inflated price.
If you look carefully you will see rows of half a dozen or more empties in areas that are normally held by season card holders (yes I know it was a non sc game last night) but my point is the game may sell out but the touts/ resellers don't.
Would the club be in its right to errm... 'have a word' with people or companies holding multiple tickets and them not being used, when they more than likely engaged with these people willingly in the past?
48,520 was a decent crowd for a school night last night when those tickets aren't prepaid and it's people's choice for each cup scheme.