The lens review industry considers “high performance optics” to possess properties located well below the high-aperture and optical correction by glass element line of the diagram. This, of course, educates the consumer to seek “optical correction” in order to fully enjoy the value of his high-resolution camera. The message is usually transmitted through:

1. 100% crops of each areas of the frame, emphasizing corner and edge correction for edge to edge resolution.
2. 100% crops of the blur circles of confusion (the bokeh).
3. Numerical “sharpness” values based on how many “lines of resolution” is measured.
4. Persecuting vignetting and distortion as defects of the lens.

Often referred as a “cold and clinical lens”, such an ideal lens has quite limited abilities, especially if the user wishes to shoot other things aside from high-contrast for “ultra-lowlight or ultra-thin-DoF handheld photography”: a lens in the red zone, below the “line of realism” wouldn’t perform as well for spaces, still or moving life capture compared to a another with much less correction and much more 3D as well as tonality.

I especially LOVE samples

http://petapixel.com/2016/03/14/problem-modern-lenses/

And all he needs is just some physics knowledge and understanding real lens work and measurement process.