Whey protein does effect insulin levels mainly if drunk alone or with carbs, i.e with no other protein (like casein) or with fat. Therefore pre-workout ain't so great. That's maybe open to debate though...
Whey protein is best consumed after a workout with carbs. Carbs in fact are the primary requirement BEFORE protein which most people just don't get. I think it was Charles Poliquin who wrote that most people would put on more mass using carb powder than protein powder, which I think means basically without sufficient carb intake particularly after workouts it won't matter if you drink a bucket of protein. Think of using protein powder without enough carbs to accompany it like taking creatine and expecting to grow on a 600 calorie diet.
You do see lots of skinny people sipping protein drinks after workouts and not carb protein mixes.
But Protein comes a close second and you need to drink both really without any fat which would delay absorption.