It's true I probably underate him, but I base my opinion on 3 or so years at Real and not just the last year, he was very good last year playing away form the wing when I saw him, I would agree, but over a 3 or so year space he's not been overly productive on the wing, similar to Luiz who isn't overly productive at CB, both players who perform better when not playing in "their position".
Also stats wise, Arsenal fans last year were quoting Ozil's assist rate on paper was on par with Messi~ etc, I wouldn't pay too much attention at written stats but again, its just my opinion of the guy who would cost us.. 65mill euros.