Skull means that those players are death (or maybe even at the spawnspot, but will check that later ). Most servers have a timer on spawning (normally between the 10 and 20 sec.) after you've been shot. So getting killed has the consequence that you can't help your team to (for example) defend/attack a capture point incl the time you need to walk to were the fighting is, so you can imagine the need for teleports for big maps