Isn't part of "plate discipline" really a matter of pitch recognition?
He's only in his second season of baseball in the U.S., and had his MLB debut this year. I think it's safe to say:
1. His pitch recognition skills have not been developed;
2. With proper coaching, he should be able to learn to recognize pitches better.
Once he learns to recognize pitches better, he will become more selective. No one is saying he's going to have Frank Thomas' discipline, but one doesn't have to have Frank's discipline to be a great hitter. Vlad Guerrero seemingly swings at everything but he's able to hit stuff all over the zone because he's good at recognizing the pitch.
The universe is the practical joke of the General at the expense of the Particular, quoth Frater Perdurabo, and laughed. The disciples nearest him wept, seeing the Universal Sorrow. Others laughed, seeing the Universal Joke. Others wept. Others laughed. Others wept because they couldn't see the Joke, and others laughed lest they should be thought not to see the Joke. But though FRATER laughed openly, he wept secretly; and really he neither laughed nor wept. Nor did he mean what he said.