There were about 8 boarding troopers and a shipload of Rebels.
Anyway, People always cite "the stormies armor didn't even stop arrows" which is untrue. What hit the stormtroopers was the constant assualt with rather large rocks. Even heavy armor can't stop the force by a large hit, it just prevents damage from a shot/blade strike. You still get bruised, and when you get enough of those hits (especially on the head) you get quite damaged. Surely some of those troopers got concussions.
The armor is not useless, just doesn't make them godly unstoppable machines.
I see it like a jockey cup, it minimalizes damage, but you still get bruised. But it could be a hell of a lot worse.
“This body is not me. I am not caught in this body.
I am life without limit.”