What really sunk it for me was that it presented football as the Biggest Thing Ever and Always Had Been in Ankh-Morpork, but we’d never really seen any hint of it at all, before that book.
Except for in Jingo.
Isn’t the story of effectively the formal game being invented? Rather than a violent street version? I guess it doesn’t work as well if you’re not from a soccer country, and indeed, the UK did have a blow up of teams formed in the late 1880s when the leagues were setup. But I suppose Fever Pitch got Pratchett inspired to do something on the misery and tribalism that the UK football scene is. And that doesn’t work half as well in the US. I enjoyed Unseen Academicals, personally, but I can’t remember a Pratchett book I didn’t.
Or football culture in general, I liked the book (specially because there’s a thinly veiled Maradona-based character).
At the start of the book, there was already an organized league with a team for each* of the guilds.
*Well, mostly. I’m pretty sure the Seamstresses didn’t field a team, and I’m not sure about Beggars, Assassins, or Thieves.
Unseen Academicals is the one Discworld book I hate. Mainly because I hate soccer (football) with the white-hot heat of a thousand suns. But hey, if others love the book, then it’s all good.