Solid sources about the tiering systems being created by lucas along with nick gillard?

Im just curious to know if george was involved with this stuff particularly need sources for it if anyone can post them.

"In this one, Anakin becomes a level nine. George knows the levels. George talked about levels and how it works. But it's not like a black belt, it's more like a ricter scale. So the difference between eight--Obi is an eight--and a nine is enormous." - Nick Gillard, ROTS DVD commentary

 "George Lucas works on a system of levels. So, on The Phantom Menace Obi-Wan would have been like a level six or seven. Now that we're on Episode III he's actually a level eight. When you move up the levels, it affects the style of fighting." - Nick Gillard, Homing Beacon #126

Thx You very much