Dybala is on 13 mil at Juve and if we're to believe the reports that Partey wants 10, that's 23 mil in wages for two players + money spent on them.
Add Auba and Özil to the list and the wage bill goes through the roof. It's not rocket science to understand that we're not going to make those deals and get another midfielder and CB in the same window.
Lacazette earns £10m a year so signing Dybala with Lacazette going the other way is a £3m increase to the wage bill (not that I believe this deal will happen anyway). Torreira and Guendouzi probably earn a combined £7m a year. With them gone and Partey coming in it’s £3m added to the wage bill, so a £6m increase in total. This isn’t even taking into account other wages that will be saved with people like Mkhitaryan, Holding and Ceballos going. That’s probably about £15m in saved wages there.