A rogue is exactly that dude, roam around and pick off the guys that are out of place, on their own or escape a team fight. It's seriously easy pickings.
Rogues have the stealth advantage so make the most of it, play clever don't take risks that aren't worth the pay off and support your team by picking off members of the other team.
That doesn't mean you can't still play as a team you can still support someone who's trying to complete an objective or slow down the enemy - you just have to think your plays through better