I use shoulder charge a lot and I'd say it's about a 50/50 situation. I get kills where I say "wow that was sort of lucky" just as often as I don't and say "really? I should have got him". You go straight up in the air for kill one second and come up 5 inches short the next. I feel like the times where you [i]do[/i] chase them up or down is because the animation activated and knew that you would have gotten it in that moment in the positions the two of you were in, so it just zooms you right to them if they happen to move a bit. And you also don't get the kill if they're running towards you, and you activate it when they're just outside of range, but you end up running into them because it takes you forward and they are also moving forward. All in when you press the ol R1/RB