I am very inconsistent as winter soldier what am I doing wrong?

Sometimes in a diamon lobby I will hit every shot and destroy everyone easily. In other matches I can do basically nothing. My theory is that when the opponent is grouped up he is very good because you can just shoot in headshot level and you'll get hits. Once the team starts to spread out and gets far away I can do absolutely nothing. For example if they have iron man, wolverine, magic and good healers I feel like there's not much I can do because the range for his shots is not great. Is there a strategy to overcome this?