I feel it's not a problem of adapting to the English Premier League and if I'm not mistaken, Joao Felix actually wants to stay at Chelsea and he feels comfortable there, but Chelsea's decision not to extend his loan period is an obstacle for him. Moreover, he also didn't want to return to Atletico which made things even more complicated, but fortunately a team like Barcelona wanted to come with a loan offer so he didn't have to think long about accepting the offer.
Now Joao Felix has expressed his interest in staying longer in his dream team and is now just waiting for Barcelona to decide whether they are able to make the transfer permanent or not. It would be another misfortune for Joao Felix if he doesn't get a permanent deal and has to return to Atletico.
Joao Felix is a player tipped to be one of the best strikers in the world. His days in Benfica were glorious but his performance reduced drastically when he moved to Atletico Madrid for a record fee. He never adapted to the club's style of play and fell off with the coach Diego Simeone which made him move to Chelsea on loan. He has so many opportunities to make an impact on the team but he also failed to live up to expectations.
Xavi gave him the lifeline to rejuvenate his career in Barca and he was performing well as he scored three goals and gave three assists in fourteen games. Joao's main problem is inconsistency in his performance but it all depends on Xavi and the management of Barcelona to decide if he will be signed on a permanent deal. But Atletico Madrid will not let him go for free because they are known for making money from player transfers.
Going back to Atletico is not an option for the Portugal players because it is glary that he is not in Coach Diego's plans. He indicated that the player has failed to blend with the team and has also refused to abide by the tactical plans of the coaching crew. He even alleged that Atletico's fans don't like Joao Felix and he would be pleased if he secured a permanent deal with Barcelona.