On top of the great comments that have already been made, I think that to be the best you need to be able to run well both ways. In my opinion one of the reasons the Americans don't do well in the championship middle distances (and endurance events for that matter) is because despite being able to run decent times on the Grand Prix circuit they don't know how to run in the sit-and-kick strategies that are so often used in the championship qualifying rounds and finals.
ELITETRACK Founder