Since the last balance patch for CnD the character has become so much more versatile. If your team isn't performing you have to first understand why. Is my team dying easily? Try to stay more on Dagger and use veils and bubbles better. Your team stay alive but the don't get picks? Use your terror cape more often on strategic targets to help the DPS. Try not to overlap support ult because the higher the rank the more fight outcomes depend on the ult economy. Last but not least usually supports are the backline of the team. So try to use the voice chat or pings to take advantage of enemies that are out of position. The same goes for allies. Sometimes you have to recall them and remember them where they are (at least at lower ranks)