You'd be surprised how many terrible players try to step in savage. I always ask them why are they here when their performance is not good enough for extreme, let alone savage. The response is almost always "because i want to", which is OK, if you're going to drag the party down and make the rest of us pick up your slack, i will not hesitate to remove that person from the party. It's always fun to see who the party considers is more needed, a good healer, or a subpar DPS with a mouth on him that's holding everyone back.
Tip: It's never going to be the healer that gets kicked.