Back in FM07 I dug up the 5 star coach rule and deduced a function to calculate any star rating. This was really handy for LLM clubs where getting a 5 star trainer wasn't much of an option. After looking at the new FM08 7 star ratings, it was identical to the original 5 star system to get the top tier, but was it the same formula?
The original FM07 formula was pretty simple. Assuming the main attribute is 'M':
Star = INT((A+2)/4)
If there was a secondary attribute ('S') then it would be 1/4th the weight of the main attribute:
Star = INT(((M*4+S)/5+2)/4)
Unfortunately the new 2 stars are 'additions' to this basic structure to give more definition at the start and end of the spectrum. There is an additional break between a 1 & 2 and the slightly better 3,4, & 5, as well as more definition at the top end by dividing 14 & 15 from 16 & 17.
The new formulas to calculate any star rating in FM08 is simply tho old formula with the 2 new steps added as separate chunks:
Star = INT((M+2)/4) + INT((M+17)/20) + INT((M+4)/20)
As before, replacing 'M' with '(M*4+S)/5' at each point gives the star ratings for training areas requiring a secondary attribute. For Set Pieces it has 3 attributes, but it's simply a replacement of 'M' with '(M*3+S+T)/5'.
Eventually I dumped the formulas in favour of an Excel lookup to get rid of a 0 star rating at 1 skill which kept making the output look untidy. I could have added another int() division to take care of it but the formula was stretching it anyway.
My Excel sheet to calculate coaching stars shows in blue what the expected star rating will be, then changes to green if you update what the actual star rating is once they are employed. Let me know if you ever see a red calculation, as that indicates that the calculated star rating was different from the actual star rating entered. I'm pretty sure it's right though as I spent 1/2 hr trying to find out why 1 value was out of place only to find out it was me not being able to count stars properly (Doh!)
