I can say with about 95% certainty that you have to have claim on the mob to get a hat drop. I did this event for about 10 hours the first day it went up. I saw about 7-8 hats drop total throughout the course of those 10 hours. Every time it dropped, we had claim on that mob. I think the killshot theory came about because of leashing the mobs and the lag/delay of the mob name's color change. If you kill the mob and it's yellow, chances are that your killshot got you claim.

Quote Originally Posted by CoolhandLou View Post
One of my party members (small party of 4) just had the Tricorne drop into his loot list.
Also, in response to Coolhand Lou's post earlier in this thread. I was in that party and I was engaged in battle with H-1/elites with another member of the party. I cannot say with 100% certainty that I or my friend who was fighting next to me didn't have claim on a mob at the time of the hat drop. We were spamming aoes.

However, I'll admit that the drop was suspiciously close to the end of the event when all mobs despawned. I can't honestly say that it didn't drop at the end of the event. I can say though that the player that it dropped to had no hate on any of the elites, was not engaged to the elites, or in the general vicinity of the battle at the time of the drop. Her only connection to the elite group was she was in party with 2/4 members who were actively fighting/aoeing H-1/elite group that was attacking a LS that was straight tanking the H-1.