You have to take into account who's attainable. Players like Antony, Nkunku and Raphina know they're good, and know the likes of Bayern, Barca, Madrid, PSG, Chelsea
will be in for them come summer. You can try to sign the likes of Kounde, Pau Torres or Schlotterbeck, but they know they'll end up somewhere better if they sit tight for 6-12 months. The issue isn't buying guys who aren't ready made stars, it's not scouting correctly and making sure the guys we do sign are technically, physically and mentally suited to eventually getting to that level. Emerson's basic ability to receive and pass the ball should have been sussed out by whoever it was at the club that went through his performances from the last few years. As bad as his performance was the other day, I think he's a decent RB who's just kind of drowning in a position that expects far to much from a player of his ability.
Diaz was a good sign of intent to be fair, he's a good athlete and a safer bet to be ready for the PL than Antony right now, imo.