I remember reading that it is easier to make a Tarmac biased car competitive on Gravel than a Gravel biased car competitve on Tarmac. It seems Citroen make theirs as a Tarmac car, while Ford is set up for Gravel, so having 5 gears and relying on torque is hurting them on Tarmac.
I can recommend the October Motorsport magazine podcast which is a WRC special – an interesting listen.
http://www.motorsportmagazine.co.uk/...alcolm-wilson/