For one it depends how you are playing, two it depends on where you are shooting and how often you are missing, three it depends what game mode you are playing. My friend runs a Striker Titan in Control where he plays as a skirmisher which means he just floats around, engaging when needed and capping when help is needed. He also holds his super back when he knows there is a Arc Blade in the room so he can take them out in one hit and the team doesn't have to deal with them. I defend objectives by patrolling. We don't run around like headless chickens. You have to play within your means and skill. Aim for the head. Each class has the same armor and shield as each other in Crucible. My friend and I usually are top 3 in the room every match just by not trying to play this like a Call of Duty twitch styled shooter. Idk if that helps but it is possible to get up there man.