Top speed he is slower than Mkhi, but not like players use top speed that much. Ozil is stronger at protecting the ball in his possession than Mkhi, so even though he is not as quick, he is less wasteful losing possession.
Ozil didn't paint him in beautiful light, that's no denying so it's same reason clubs wouldn't pay huge sum taking away from Arsenal despite on his days, he is amazing. You see players like Ox, Sirgurdsson moved for big money despite their whole career is lesser player. So Ozil took the punishment for his unprofessionalism.
Ozil was not and wouldn't be the last who try to escape Wenger's Arsenal. Someone like Vieira who Wenger had great influence took him from Milan and made him into of one the finest midfielder in his generation and Arsenal legend, didn't have the best with relationship with Wenger is quite telling.
2 wrong doesn't make a right. So both Ozil and Wenger are to shoulder the blame. However, Ozil moves away from Arsenal would be him correcting his mistake, and make it right.
While expecting Ozil to be able to replicate his form at Madrid, which he was not that terrible like his Arsenal big games form, is unrealistic, there is hope he can perform to acceptable level, which Mkhi performance has not been recently.