I had the same problem too with my Man City. I made a few changes and this stopped.
Defenders and all other tall players with good heading in the team - marking tall players (Richards, Sakho, Huntelaar)
Def mids and ctrl mids - Man mark (Palombo, Veloso, Ireland)
Shortest player (Striker/Winger esp) - Close down corner (Robinho)
Full backs - Mark posts (Garrido, Onouha)
Fastest player (winger/striker) - stay fwd (Wright-Phillips, Pandev)
I also scored goals on the break with this as the one who's fwd will run with the ball and the player who is closing down the corner and the ctrl mids offer support during the break. Try this!