Some of the 93:20 tickets have been bought by companies to take clients to the games they wish to see eg. Chelsea, Man U and the Scousers. Guy behind me in 209 - who has a chunk of tickets - says he struggles to give the tickets away for games like Bournemouth.
The Club has to set some tickets aside for the Women's and Youth Teams. Sometimes people can't get back in time from fixtures to watch the first team so there always likely to be a few empty seats - which can't be sold on. I've noted that the Women's Tram have been moved to 93:20 and maybe some of the Youth Teams have to - thus reducing the empty seats at the bottom of the North Stand. One of my work colleagues plays for Subderlabd Women's Team and they have been moved from behind the goal at the Stafium of Light because empty seats look bad on the TV.
The main factor for some empty seats is that season ticket holders don't turn every week and so be it. Our crowd figures are based on seats sold (and a small number of tickets committed to youth teams etc). That's the way it's been for as long as I can remember and it happens this way across the league.
Yesterday's crowd number was outstanding. Selling out an expanded Etihad (including a great following from Bournemouth) can only be good!