I'm probably just being thick, but I've never really understood how that works.
If the blade length remains the same, it doesn't.
Interesting other example for you on one reason why I think high middle nats that pick up better are a bad idea for those of us who don't use high middle bats anyway:
Squash racquets are usually grouped in two ways - weight distribution and shape, weight being either head heavy or head light and the two common shape types designed for either power or control. Last time I changed racquet it was from two almost identical shapes with the same head size (which affects power). The first one was head light, with most of the weight of the racquet higher up towards your hand. The second one was way lighter (100g rather than 140g irrc), but designed so that all of the weight is in the head of the racquet, because that's where you're hitting the ball. Same shape, close enough to the same price, essentially the same materials, one bottom heavy and one that picked up like a dream. I hit the ball WAY harder with the bottom heavy one.
Bought some bats that had more weight low in the blade than I usually had before and discovered exactly the same, which makes sense - for all the talk about middle position etc, weight behind the ball is king. So for those of us who don't happen to hit the ball high up the blade all the time, high middles are daft. No point having that extra weight in your bat if you're not using it. Shouldn't be a surprise really, it's exactly how a mongoose works. Or a sledgehammer.