He had an excellent first season there, problem with Arsenal is they constantly try to accommodate attacking players and whack the balance out of their team, and dont give responsibility to attacking forwards or midfielders to defend, that leads to the central channel getting over run, while their defense is beyond gash. Admittedly he has been hot and cold this season, hes a very good player, but they are a bit like us the year we had three managers at the moment, so much turmoil at the club. Club has been badly run for a few years in my opinion and the players attitudes have been awful and not committed, its a massive shame because i would have looked up to Arsenal as a great model only 4-5 years ago. Inevitable after Wenger really.
Arsenal needs a cull, or to find a better balance to their team, but id be keeping Torreira if i was them. Dani Ceballos is another excellent player. While they have a potential gem in Matinelli. Sako is class as well. So there are decent building blocks there.