What I mean is that a potential Khornate Admiral probably has to...

-be good enough to not lose significantly more than their peers
-be able to intimidate rivals and underlings
-be able to backdstab and undermine others, and resist attempts for others to do the same
-have sufficient strength of personality to get some cohesion out of these independent-minded forces he has to work with
-be able to maneuver situations such that it brings the blessings he needs to get things done from his patron (ie, do enough of the right type of slaughter and ritual to get the forces he needs)

Note that being the best admiral is... not a major part of that list.