Mark of Pain radius based on target size?

Not sure if I'm just imagining things, but it looks like the radius that other enemies will be affected by Mark of Pain is based on the size of the target that has it.

I don't have any screenshots, but when I use MoP on Giants it will hit other enemies further away. On smaller targets like the annoying Jade Scarabs in the desert, they almost have to be right on top of the MoP'd target to get affected.

Does anyone know if this is the case, or does it have a fixed radius like the other Necro curses? It's a pain (no pun intended) trying to MoP something and have another target that is fairly close not even be affected by it. I do realize that if the radius got too large, this would be one very uber skill. Just wanted to know if anyone else has seen this or not.

i have also noticed the radius varies and have been trying to determine the cause - i'm not sure if it's target size or what, i haven't noticed

but yea, sometimes it will work out nice, and sometimes i'll have the marked guy crowded by reds and only his bar goes down

gotta tell ya, a successful mark placement will make the fight. i'm learning to pace myself and not let it fly right off; sometimes a good clump comes later in the fight.