High K/Dr doesn't guarantee that you were actually helping the team.
After killing enemies, did you:
-Go back to buy items.
-Go push lanes.
-Hop in jungle.
or
-Destroyed turrets?
If you did any of the first 3 as an AD carry, then you did it wrong, unless:
You were low on health, your team was absent, and there were some healthy enemies lingering.
You can still be blamed for not telling your team to help though.