I don't think Julian Alvarez decision to leave Manchester City for Atletico Madrid is a good move because of the fact he had a greater chance of winning trophies at Manchester City than Atletico Madrid and also he would have seen more playing time if he should have been patient. Even if he scoring goals and become an important player for Atletico Madrid, I don't see him achieving anything with them. Every player wants to be a starter so I don’t blame him for leaving City but he should have gone to a club like Real Madrid where he could win trophies.
Man City might get relegated if they lose their court battle over the 115 charged that are levelled against them. Also he wasn’t starting much at Man City. Maybe he felt more comfortable moving to Spain as he’s Argentinian so that’s his native tongue over there in Spain.
Sometimes players move for reasons other than the club. Could be his girlfriend is happy in a warmer climate with a different culture and foods.