A lot of discussion has been going on about hats in tf2 about luckiness and how long it takes to play to get your hat. Found these images at Source OP IMO These are the most accurate Item Drop graphs for TF2.
I've got so little luck (a 2 to be exact, I have a 10 in everything else of course), yet I got 2 Soldier's Stashs' within 3-6 hours (don;t remember) of each other. Something's wrong here.
Now divide those odds by like <Server population>/2 .... b/c i think they hand out drops in pairs. making it like 16x harder on a full ego server to get 1 xD
this is based on guessing not fact; so don't be quick to correct me unless you got the real deal.