In 12 matches, Arsenal have won nine, drawn one and lost just those two games against City.
The Gunners have kept five clean sheets in that time and conceded 10 goals, three of which were when Mari went off at the Etihad last summer.
There has been some dispute over how much Arsenal will end up paying for Mari, with anything up to £14million being touted.
But whatever the fee, it appears to be a bargain deal by the north Londoners.
