William Lemaster

This is a Glicko-2 rating — the same family of system used for chess and for iRacing's own iRating. Every GT3 league race is treated as a head-to-head event: you gain rating for finishing ahead of drivers and lose it for finishing behind, scaled by how strong those drivers are. Beating a high-rated Pro is worth far more than beating a backmarker.

• One combined ladder. Pro and Am drivers race the same car on the same track, so they are rated together. Division is just a label; the rating is earned on track.
• Recent races count more. Each race is weighted by age (half-life 8 months), so current form drives the number. Only the last seasons are counted.
• Uncertainty (RD). New or returning drivers carry a high ±RD until they have raced enough. The floor (1621) is the rating minus 2×RD — a conservative estimate used for promotion decisions so a hot streak on a small sample can't promote someone prematurely.

Counted races: 21 total, 15 in the last ~year.