The Athens decision years ago has to do with the bi-lateral agreement with the Greek government. The way I understood it was that the Greek government set the fares as well as the number of seats and thus Olympic would always be cheaper than QF. That could be urban myth but Athens has barely rated a mention in QF talk since the mid '90s for various reasons. As you say, a high rate of VFR traffic (and thus low yield) probably played a large part also.