His potential has nothing to do with incomplete trainingsweeks not being effective.
You can not call it 4 weeks of training if he hasn't really had 4 weeks of training. I can understand that others sound patronizing but it sounded as if you were complaining that something was weird because your players hasn't popped in driving while the reason is that you don't really give him near enough minutes of training.
Crunchy! If you eat fast enough