In the penultimate step if you plant your foot (as most do) slightly in front of your COM you will loose speed. If you are able to plant in the penultimate with your COM above or in front of your foot you won’t lose as much speed, thus having a big advantage for the jump.
F.e. Carl Lewis and Mike Powell planted to the side because that way they were able to virtually plant under they cog. A more refined technique allows you to plant more directly under you.
Sebastian Bayer is the best example I can find nowadays:
At the very initial moment of foot contact of the penultimate:
And how it looks for the average joe:
Anyway meanwhile I figured out that that advanced type of lowering is the result of very tall running and excellent posture throughout the last steps. Just watch Bayers 8.13 slow mo and you will see that.