Quote from CardinalMDM
I can definitely understand the issue people have with proc coefficients. I don't mind when a tooltip says "X has a chance to Y" without defining it when it comes, in particular, to skills that either hit bazillions of times, or that can be spammed tons of times...because at least if the proc coefficient isn't defined, you're still likely to get it to proc a certain amount of times in all those hits. But Life on Hit isn't a skill with a percentage chance, it's just very direct..."Each Hit adds +X Life." Boom. Done. That likely shouldn't have a proc, the "chance" isn't defined in that anywhere.
I think what he means with hidden coefficients is that some abilities gain more from Life on Hit than others and that this should at least be indicated somewhere.