The idea is that you're retracing your progression, except that this time you've got the benefit of additional workouts and heavier weights, so it should be easier to get past that hump.
The way I think of it is this: You're trying to jump across a gap and every week it gets bigger. Each week you start your run at the same spot and make the jump. Now you can't make the jump, so you decrease the gap and start back a step further than normal, getting a little more speed before hitting the gap. You're jumping a gap you could already jump, except now you're able to run faster before hitting it.
It's a bit fucked up, but if you think about it this way it is easier to picture what you're actually doing. It makes sense to me LOL
