What about a simple scale of 1-100? They could have different breakdowns, then an "average number" would be assigned to the stallion in the end. It could be a simple box plot with outliers and quartiles. That would be a good way to find the right range for the stallions average production rates, and it would eliminate the harsh effects of the outliers- for example, a stallion throwing one amazing MSW in mediocre 40 foals, or throwing one dud in 40 where his foals are normally good runners.

so the math would look something like....

0-----------------25% quartile----------------Median---75% quartile---------100

The median here is closer to the 75th quartile, so lets say that 68% of his foals turn out to be winners or better.

They could have different number breakdowns such as-

2y/o sire

3y/o sire

4y/o sire

5+y/o sire

Broodmare sire

Stud-Qualifyers

MSW

SW

SP

Win

Place

Turf

Dirt

Steeplechase

Distance

Sprint

etc...

So for example-

Stallion A has 20 foals. He has produced two MSWs and most of them are winners by the age of 3. So there could be a point system devised based on how all the foals performed, and also based on using the plot box to eliminate any "uncharacteristic" superstars or duds that horse produced....

You might get numbers like this? I don't know how you would get an average number, but it might be worth looking into.

2y/o sire- 60

3y/o sire-83

4y/o sire-65

5+y/o sire-30

Broodmare sire-56

Stud-Qualifyers-05

MSW- 10

SW- 33

SP- 45

Win-91

Place- 95

Turf- 62

Dirt- 48

Steeplechase- 26

Distance- 28

Mid-range runner- 46

Sprint- 24

So looking at these numbers, I could probably assume the following (the #s were completely made up, not based on any horse living or in the game)-

Obviously, this is a stallion who has the capacity to produce lower level winners and stakes quality runners, but isn't likely to produce your next superstar. His foals perfer the 7-9 or 10 furlong range, and run better on the turf. His foals generally mature into their prime as three year olds, but don't rule out a good two year old or aged runner. He seems to be a solid sire overall, perhaps nothing spectacular, but paired with the right mare, he has the capacity to produce some really nice foals.

Wow, that was a lot for me, since I'm terrible with math, but I hope you understand what I'm getting at. I'm not sure how it would all work out, but if anyone can decipher it, Shanthi can!