Apparently the rumour is that Martinez didn't want him back probably because he wouldn't get the minutes he needs now that we have Atsu and are close to signing Henen (who is a Belgian and another "next Christiano Ronaldo" lol) so we don't have the room for him.
If he couldn't get on Everton's team as a starter he's bound to struggle at Sevilla too but I hope he will do well at Sevilla.
Did you ever think that Martinez was benching him for the same reasons Lucho has put him out on loan? It's called man-management, this is not some video game where you just give young players game-time and they become world class.
That's cute and all but we all know how much you'd like to have him back. With Everton being in the Europa league they'll need more depth than they did in Roberto's first season.
You probably can't name a single player playing for Sevilla aside from Denis Suarez but you're certain he's bound to struggle there. I know several Sevilla fans who are over the moon about getting him from us because he's a better attacker than their current wingers, although they say Unai may have to alter his formation a bit, although I disagree as Deulofeu doesn't have to be used as an out and out winger as his Barca background may suggest.
Yes, Martinez almost certainly benched him for the same reason Lucho is loaning him out again. That's the problem. Everton is not such a good team that they can't afford to let him play. He's going to Sevilla for the purpose of getting game time. Players don't develop sitting on the bench. You're so quick to say it's not a video game where you just give them playing time to help them improve but to be perfectly fucking honest with you that's exactly how it works. Busquets didn't walk into the team one day and kick Yaya Toure out of the team. Pedro didn't just slip from the shadows from out of nowhere and outperform Thiery Henry from his first day. Xavi rode the bench early in his career behind Pep and didn't get fully going until he was near his prime because of it. If a player is to improve they need to not only be told how to improve, but be given a real chance to show that improvement. He has already shown he is able and willing to track back and help defend. His problem now is decision making and there's no better way to improve that than to actually play.