It's what I've derived from the personal trainer. They used to give us 15SP for 64T, now they give 4% (well I don't use that). Therefore:
1%=approx 4 SP (or individual skill percentage, like fitness, crossing, tackling, reflexes)
4%=1 skill grade (15 SP/%)
20%=1 star
All these are calculated with respect to the lowest quality scout. IE 100%=6*
I guess this helps for those confused.
