tenacioustoasterPipes have always been affected by where they hit the person
actually no, that was always a misconception. it's a matter of being rather expensive for the engine to map the pipe against the player's collision since the pipe's collision is arbitrary, and it had to be snug to deal max damage. so it was always basically random how exactly far away the pipe was.
I bet what they did was, when pipes blow up on impact, they turn into little dots instead of being rotating vphysics objects, or they're spherical or something. that would make it possible to map exactly against the hitbox without doing crazy stupid math.
EDIT: Or they could just flag the player they hit or something.