Maintenance for the week of October 5:
• [IN PROGRESS] ESO Store and Account System for maintenance – October 8, 8:00AM EDT (12:00 UTC) – 12:00PM EDT (16:00 UTC)
Sadly, I don't anything about it other then once you reach it, any more points above it is worth half its value.
The higher you get over the softcap, the less you get. For instance, I have a +1750 armor buff, but since I'm softcapped I only get about 400 armor from it.
Currently it doesn't seem to be worth putting any points into something once you hit the soft cap. I can be 100 points over and not notice a difference.
As for the graph, I think it may have to be one of those things that a set of dedicated players with great math skills will have to figure out. I don't think Zeni will show that information is any easy viewing way.