Valverde wanting Arda out is just a rumor at this point. The man didn't even meet the players.
Arda will show in trainings if he is better or not than Denis. Last season, he showed that. If this season he is going to show again he is the best option at LW after Neymar, he should play. Simple as that.
Arda has a contract with us, and he doesn't want to leave. End of. You don't end contracts just because you feel like it. What's the message to the future players we want to sign? 'We give you a 5 year contract, but if by some reason you don't play well, we'll make sure you leave on your own after two years'. Let's not forget Arda sat out for 6 months with no football, before signing for us. Football fans have short memories, but the club should be above that.
Bartra, Arda or whoever. It doesn't matter. Selling or buying players is mutual, and contracts make sure of that.
Denis has showed little so far. Like Gomes. Arda, as hated as he is, showed more than both taken together. You're right about Deulofeu, but I'd like to see him in action first.