Well, trained players were 19, 20, 21, 21, 23 yrs old. Not terribly young, I admit, but still...
My point is: in, say, 25 overall weeks of training I've had no pops only three times.
One of them was in the middle of a season, and I sort of expected that.
The other two times were in wk1 of season 8 and 9, and both after a F/TB/SC streak.
I'm not saying it's necessarily a bug, but it's hard to see it as a coincidence either. I can't help but think there's some kind of anomaly due to wk1 being split in two different seasons.