I still find 60+ million a lot for Zubimendi, we are talking about way too much for a player that doesn't deserve that much money. But Real Sociedad knows that they are in it for the long term and need the money and Arsenal can afford it, whereas the situation, Arsenal is in is a tricky one because for three years they have been a second place team and the whole "always the bridesmaid never the bride" thing is getting a mockery from the fans not only from other teams but starting to be from their own fans too.
This is why they are not afraid of spending a bit more than they should, because they want to be the first place. Gyokeres was a situation that took too long and Sporting made a mistake, that has to be the most careful place.
I agree, I think Zubimendi only popular he play for Spain, while his performance is like a mediocre player.
I understand Arsenal need new midfielders, maybe they don't have enough time to scout young players and train them, so they prefer to pick midfielders who play in top leagues. It's high likely Arsenal will play with Rice and Zubimendi, Partey will stay on the bench until Arsenal sign new midfielders, then they will sell Partey.