All of that is clear to you
WOW From an overall 1170 minutes he played
but unfortunately for him he just generally doesn't seem like he'd be good enough even if given two or three more seasons to adapt.
How on earth you reached that conclusion ! What would prevent him from being the World Class Arda he was for long time at Atleti ? You're just saying it like you've already seen the future .. I repeat he is Arda not Espinosa, nothing would prevent him from performing better than Rakitic by the beginning of the coming season .. If you was judging Rakitic based on his performances in the 1st half of 2015-2016 like you're judging Arda you would've been saying the same about Raki now .. he won't be good enough even if given two or three seasons, although he just needed a couple of matches after mid season and he turned into a GOAT !
Talking about Roberto, If just Enrique didn't suddenly change his mind and kept him last summer, Roberto would've left as a player who has never proven anything at Barcelona .. Based of your logic he would've a player who won't prove anything even if given two or three seasons .. Roberto has played 2575 first team minutes before the start of 2015-2016 .. that's more than double the minutes Arda got with Barca's first team .. Roberto has proven NOTHING in these 2575 minutes .. then proved EVERYTHING in the last 2800 minutes he played .. the 2800 minutes that he would've never played if Enrique's logic was yours
- Not to forget mentioning that Roberto has always been here, learning Barca system. When he reached the 1st team he was already totally adapted to it