So I have my foundation sire who was just dominating at a mile in my breeding shed and just about every horse that he sires is amazing as a 2yo, with reached potential bars and everything, but the moment they become 3yos, they lose so much potential and go from graded stakes winning champions to allowance losers... Anyone else having this weird phenomenon?

I've had a few excellent two year old's that have not been able to cut the mustard at Group/Grade 1 level at three. I've just put it down to not training on..