Haven't seen Lo Celso play, is he any good?
Yeah he's easily worth the 55m they're paying. He's quite Lampard-y, I don't think his passing is on the level of the best playmakers, but he's really good at carrying the ball forwards, and getting in the box to score - not those late runs like Lampard though, he's usually in the box already.
He beats players a lot in midfield, which is something Pochettino seems to love. He does the thing where someone's pressing him and his first touch nutmegs them or knocks it round them. Might find that harder to do in a more frantic league, but Mousa Dembele and Dele Alli did/does it a lot.