Emery barely played him in Sevilla, Barcelona let him go without even thinking about it for next to no money, Martinez had a period where he benched him more often than not or gave him 20 minute cameos as well (to add to the annoying fact that Deulofeu was goosed when he started any game), now Koeman's doing the same as the previous... everyone else.
Defo something in the managers mate, not Deulofeu, can't be the player having some kind of attitude/fitness problem, only 4 managers/teams have let him go easily or not played him. Yup, god damn managers, not knowing as much as you do about a player from actually seeing him in training on a daily basis. Idiots, the lot of them.