An individual usually retreats back if they're in danger of being downed or on their last down to make their teammates suck up the blows.
Ideal weapons of choice is frag grenades or power weapons to take out the horde.
Another Player: Yep they're hording together because they can't play this game on their own.
*Reads bio of CrAzzzzzY YeTi*
"IF U BEAT ME ITS CUZ MY TEAM SUCKS IF U KILL ME ITS BY 2PIECE OR POWER WEAPONS THATS IT"
Gears of war player: But..doesn't power weapons eliminate the horde problem?
Another player: Tell that to the yeti over there >____>