My guess is: how much damage you do compared to everyone else (Sampire) or how much you heal for (speaking solely for myself here, I can keep people alive against pretty much ANYTHING as long as I'm alive)
So, say that there are 60 people at an Event and 30 of them do 1,000 points each in between tanking, healing and damaging, and the other 30 do, like 300 points each in between their tanking, healing and damaging, but the "top attackers list is limited to only 10 individuals, there is simply NO WAY that any of the 30 players doing 1/3 of the top attackers were doing, can EVER DREAM to get in that list......
As long as there are uber templates pushing up the top damaging points, the lower damaging players simply DO NO HOLD A CHANCE to get into that list and thus to get a drop.
The system should simply award a random chance at a drop that is exactly the same whether one does 1 million points of damage or 1 point of damage. This only would do away with the uber suits and billion gold costly gears...
I see with Event items, exactly the same pattern that there was with Powerscrolls.
Those with the best gear and most wealth, thus capable of holding a tight control of Champion spawns, would get scrolls a go go and sell them for tens upon tens of millions thus getting even more wealth so as to be able to buy even better gear, and maintaining a tighter control of those spawns thanking to their uber superior gear.
And now is the same with Event items. Those who can afford uber items and billion gold worth suits, push the edge higher for the "top attackers'" list (create a wider gap with the lower end players participating) and thus, get higher chances at getting hundreds of millions gold worth event items which allow them to even buy better items and thus push the edge further up, being able, thanking to their upwards fine tuned gear because of the wealth coming from the sale of event items, be able to get further better items.
As I thought this was not good for powerscrolls, I see this as not good also for event items.
It was a big mistake back then to let the same few players get all of the powerscrolls and I also think it is a big mistake to let the same few players most always get Event items.
Others may think differently, but that's how I see it.