The retirement percentage is built in to the aging percentage.
*AGING means one notch loss in all significant categories
If a player meets the eligibility requirements their chance of retirement decreases by 25% and their chance of aging decreases by 15%. AGING W/ELIGIBILITY:
If age 20-28, 1-100 safe
If age 29, 1-5 ages, 6-100 safe
If age 30, 1-25 ages, 26-100 safe
If age 31, 1-5 retires, 6-35 ages, 36-100 safe
If age 32, 1-15 retires, 16-45 ages, 56-100 safe
If age 33, 1-25 retires, 26-65 ages, 66-100 safe
If age 34, 1-35 retires, 36-75 ages, 76-100 safe
If age 35+, 1-45 retires, 46-85 ages, 86-100 safe
The retirement percentage is built in to the aging percentage.
HOW IT WORKS
At the end of the season, age is determined for each player in the league.
Let's say a player is 29 years old and qualified was eligible at their position by ranking 4th statistically.
A 29 year old has a 40% chance of aging and 10% chance of retirement within that 40%.
Since the player was eligible at his position, the chance of retirement is decreased by 25%, so he eliminates his chance of retirement. He also decreased his chance for aging by 15%, so he now only has a 25% chance of aging.
So to recap, the player has a 0% chance of retiring and a 25% chance of aging.
GTFO will then use a random number generator to generate a random number between 1 and 100.
If the number is between 1 and 25, the player AGES (loses one notch of every significant attribute)
If the number is between 26 and 100, the player NEITHER ages nor retires
So for this particular player, say the first random number generated is 24. The player stays in the league but loses a notch of attributes.