Actual Intent
I actually didn't do this research on purpose or anything but I stumbled upon it by chance. What I actually wanted to do is to check out how many kills I make during my time in World vs World. After doing this multiple times I realized that there are an obvious correlation and pattern between the kills and Heavy Loot Bag drops. Well, it makes sense, but it surprised me anyway.
Procedure
So, to count the number of kills I was kinda lucky that I hadn't completed the avenger title in Guild Wars 2: World vs World. If you don't know what it is, it requires you to kill 250,000 players in World vs World. That's a lot and yeah, I have managed 67k or so over the four to six years, I've been playing currently (I play other modes besides WvW too, by the way). Anyways before starting my World vs World session, I noted down the number represented in the achievement. I did this via my lovely Python console creating a new variable "kills" by setting this variable to the number of kills shown in the achievement. Next, I subtracted kills from the current amount. The result is the delta kills or the kills I've made up to the point I did the subtraction. As simple as that.
Realization
At some point, I noticed that I have almost always four times as many bags as player kills. This means that apparently about every 4th player that has been killed drops a Heavy Loot Bag. Now, these 25% is only an approximate that works at ~1800 player kills. To nail the number down to it's exact, you would have to actually collect and keep all that data. Still, this seems solid enough to approximate the number of players you've tagged, which also died, by multiplying your amount of Heavy Loot Bags by four.
