Prepatch I had 8 ath. By that time I could kill an enemy mob of 10+ players, just by running in and out, slashing in random directions. But that's (well, I think it's better that way) not possible anymore.
The only classes that can really survive with low athletics are either pure cav lancer (I'm being dehorsed too often as cav to not invest points in ath), or some weird uber roof sniper, or a pure str/crushtru build. Pikeman is maybe the class needing the most athletics, because you'll have to flee very fast if your mates are killed.
I've seen some people that have very low athletics, still managing to make very good kills in melee situations. I really don't know how they do that.