Honestly it's sad to watch him flop over and over again. He is the guy with good pace, he is fast and he can really change the rhythm of the game, unfortunately he obviously lacks football IQ.
In every club exactly the same story:
Sevilla - at first he was doing OK and than he disapeared. Emery said:“He has incredible qualities but lacks others. Put him out there, one on one and ... pfff, but make him play football with teammates, on a big pitch, and it’s hard. He doesn’t have the maturity or capacity for sacrifice yet." and that sentence sums up Deulofeu as a player!
Everton - The same story like in Sevilla. He was doing really really well in the beginning and than again he end up in stands.
Milan - I am afraid that the only reason he didn't fail there was the fact that he had only 6 months time to do it.
Barcelona - Neymar left, Dembele gets injured and he flops again in spite the fact that he had enough chances to prove his qualities. FFS Vidal is now in better position than he is and for 2 years Vidal was playing as a backup RB and not winger.
Deulofeu is almost 24 now, he could have been a really good player but unfortunately he'll never live up to his potential. He will probably go back to Italy and he will again have good few months and than problems will begin. It makes me sad to watch a player with such a big talent wasting it over and over again.