Exactly. A one-position trained 18-yo can achieve between 10-12 pops in his first season of training. So if you are choosing between a bad 18yo or great 19yo, that may be a hard choice. But you can always find decent 18yo in a draft class and those are always better than even A+ 19yo, considering 18yo gets a full season of training of course.
I will also give you an example: in the same season I drafted a 18yo PG with very bad shooting and a 19yo SG with very bad passing. They both received equal training in last three seasons and a half. Look at them now:
18yo (now 21yo):
Weekly salary: $ 13 609
Role: regular starter
(BuzzerBeta)
DMI: 319800
Age: 21
Height: 6'0" / 183 cm
Potential: allstar
Game Shape: proficient
Jump Shot: tremendous Jump Range: mediocre
Outside Def.: tremendous ↑ Handling: sensational
Driving: wondrous ↑ Passing: sensational
Inside Shot: pitiful Inside Def.: respectable
Rebounding: pitiful Shot Blocking: atrocious
Stamina: mediocre Free Throw: strong
Experience: awful
19yo (now 22yo):
Weekly salary: $ 16 592
Role: regular starter
(BuzzerBeta)
DMI: 109600
Age: 22
Height: 6'4" / 193 cm
Potential: allstar
Game Shape: strong
Jump Shot: tremendous Jump Range: proficient
Outside Def.: sensational ↑ Handling: sensational
Driving: tremendous Passing: average
Inside Shot: pitiful Inside Def.: respectable
Rebounding: mediocre Shot Blocking: respectable
Stamina: inept Free Throw: respectable
Experience: awful
They are different players for sure, but I like first better - he will be much better at the age the second player is in now.