Originally posted by Bluesman
That's because as your attributes increase your train percentages decrease
pretty much this, but to be a little more specific, with you QB for instance, when first created, throwing may be 27 and your training gains may be 75% intense, 50% normal, and 25% light. As you train them and your throwing goes up, those training gains will go down, so when you have throwing trained up to 30 from 27, now your training gains may be 70% hard, 45% normal, and 20% light. (%'s just random for example purposes and not accurate for attribute at 27)
Buying training enhancements can lessen the effect, but as your attribute goes up, your training percentages will still drop.