Unresolved

What causes racing atrophy?

I have two pilots: a more experienced one and a more basic one, which I recently acquired. I've noticed that their stamina atrophy levels differ dramatically after the recent changes! Specifically, the first pilot's stamina atrophy: https://igpmanager.com/app/d=driver&id=14646781   is only 0.09%,
while the second's: https://igpmanager.com/app/d=driver&id=10716629   is a whopping 1.52%. What's the reason for this?

PS: It's funny that the AI assistant answers the question about atrophy based on information that has been outdated for several months

Doctor and age are a factor from what I could see 

It most likely depends on the racer's rating (number of stars). Similar to the fact that those with fewer stars train much harder than those with higher ratings