Only lack of downforce and excess of weight
Or also turbo engine's characteristics? I.e. torque
I remember that Button, in a pre-season interview which I am unable now to find, said that there was a difficult balance for high-speed corners and that a driver, seemingly different from previous seasons, has to leave the car sliding the corner and can return on throttle only at the very end .. But maybe it was a MP4-29's problem. Watching Rosberg's Suzuka pole, it was taking corners also with mid-throttle