Don't understand your last point
The other point would make sense if I was making a direct comparison to Xavi and Pirlo, although I would argue that with better players around him he'd have as much impact as those two have had on the sides they have been in. To pre empt your next response, they both during their careers have generally played with a better calibre of player than Ozil plays with at Arsenal.
Ozil was a key player at Real Madrid and Mourinho was quick to acknowledge as much, but then we get Florentino Perez who came out with the banal statement about wanting good looking players in his side, and Ozil unfortunately looks like the son of Marty Feldman.
Either way rightly or wrongly he was sold to help pay off the transfer fee for Gareth Bale, the same way Alexis was sold to pay for the transfer of Luis Suarez.