Doping with EPO and transfusions improves endurance and speed at threshold. Both useful to footballers especially in the final 15 mins of a gruelling game where that edge can mean beating a tiring opposition.   
Doping with anabolic agents improves power and acceleration -  very useful for explosive attacking runs, jumping for headers and bruising defending.   
So I conclude that it is naive to think there is little or no football doping, given the ££ involved, the egos and the lack of policing.