What the assistant thinks is unimportant. During a match go to the analyse screen, click the left option and check average positions yourself.
Most often one of the MCs will be more attacking and he would be more advanced on the pitch even though you dont see it in the tactics screen. That way the gap between MCs and Strikers is smaller, same with using a more defensive MC and defense and a less attacking striker (TMsupp, Complete FWsupp, DLFsupp, Trequartista) they will all fall back to link up play meaning there is less of a gap.
One other thing: usually its best to not have the MCL on attack when the left striker is on support because that part of the pitch will get too crowded. Instead put attacking strikers in front of attacking MCs.
Another thing: dropping deeper will increase the gap, pushing up higher will make it smaller.