Actually it is. And it's not just "years ago". It's the near past and distant past. So you should just stop that now. We can view player based on their past, in which Arda has shown to be a better player than Roberto, and we can view a player based on future potential. Roberto has age, knowledge of the system and playing time in his favour (as mentioned before), but Arda has been here for a very short time thus have limited knowledge of or experience in the system. Not to mention being match fit or having rhythm in general (i.e. regardless of system) - something Roberto does benefit of regardless of him having had to play many positions. He has played football. Matches. That's the point. That'll change (like it did with Suarez) and we'll get to make a proper evaluation of him. Given the context, it's foolish to evaluate now.
Also, mentioning those players doesn't make much sense. They are not Arda. Arda are not them. For every example you being up, there are players that have excelled into their 30s. Arda is 28 (soon to be 29), and we dont know when he will decline. It's speculation and has nothing to do with what we're seeing now. Now, if Arda is playing like he did against Malaga for the next year, i.e. not playing like he used to at Atletico, then we can begin to make some conclusions. By then he'll have had enough time to settle in and everything. But until then, let's stop with the nonsense.