The "pull hitter" as I'll define it looks for pitches middle/middle in to pull. If he doesn't get that pitch, he doesnt' swing until he has two strikes. Then he looks to hit it where it's pitched. But early in the count, he looks for something to pull hard and deep.
The change in approach would be to hit a strike where it is pitched at any time during the count. If the first pitch is a fastball middle out, look to hit it hard to the opposite field.
It's a change in approach. I understand the difference. I'm just not sure how moving from one approach to another helps develop power. And I'm not disagreeing with it. However, it seems counterintuitive. Just wondering how hitting more to the opposite side helps develop power. And looking for a detailed explanation.