alt Hacker NewsIt's annoying they didn't plot the new and old "perceived" curves on the same figure, but if you pay attention to the y-axis, there is a very big difference.
In the old plot, the bottom quartile has about a 50 percentage point margin between actual and perceived performance while the new one is 30 percentage points, which is a 50% difference between the old and new curve. The second quartile has 3x more margin in the old version relative to the new one.
So what does that change? If there's no error bars on the graphs you can't discuss significant differences easily. And if they do differ, plotting differences will yield the U shape curve.