Looking at the tracks today according to racing and sports the track at Hawksberry is a Soft(5) with a pent rating of 5.06

But at the same time a pent rating of 5.2 is given for Werribee but its rated a Good(4).

Now I know there is only 1 difference in the track rating from 4 to 5 but I would have thought in these days they were based off the pent rating. Obviously not.

Anyone care to explain why ? I assume different soils, grasses, expected sunshine before the races start, etc.