Cool, I really like this site. From the "Overall Champion Matrix" I'm seeing that her damage, kills, and assists really aren't that far outside of the average. The extremes it does show for her are deaths and win rate.
I also see that her win rate for longer games is drastically lower. Her play rate has been decreasing steadily from the last few patches.
Yes I see that her win rate and play rate are high.
I don't see how this supports your want for damage nerfs though; just saying that matrix shows it's not that out of the ordinary.
Perhaps her R is more of the issue. Her ability to reposition and ability to engage on team fights with that might be the bigger problem. Her abilities are a lot like Xerath, but Xerath is immobile and in my opinion less fun because of that. I think fun goes a lot into pick rate.
As far as the win rate I think it comes more from the mobility that her r allows her. Personally I don't feel as though dashes should go through walls in jung. Hops yes, blinks yes, but you can't dash through tree or rock.