He played some games. He even scored in a derby against Arsenal. At Barca he wouldn't get that chance. Not yet anyway. It is wise to let him one more year at Everton, depending on how the ban appeal goes.
He scored vs. Arsenal in..... you guessed it, a 10 minute cameo.
I don't mind him going out on loan, but definitely not at Everton. They play scatterball so much that he is often isolated. He's not learning how to play in a tactical system, just a wild storm of "survival of the fittest", how the hell is he supposed to improve? He doesn't get many minutes, he's not a focal point of the team, and he's not playing in an environment that has improved him at all (other than Martinez making him track back).
Back in the B team, Rafinha looked like dog turd 1/2 the time while Deulofeu was the star. Now the tables have turned because of one year of crucial development or lack of. If Deulo went to Celta, he'd refine himself a lot and get on the right track. Lucho did well in bringing out the best of Rafinha, even gave him an improved role (vertical box to box AM, as opposed to his previous role as an isolated support striker almost). I see no reason as to why he wouldn't be great at improving Deulofeu too.