The reason recoil applied to the shooter decreases is that the amount of energy absorbed by the pad is turned into the heat of compression, and is not conveyed to the shooter.
Also, lengthening the time of collision spreads the same energy pulse over a longer time.
So the peak is lower for the same energy input.
A somewhat fascinating comparison is the difference of a very light weight person, and a very solidly built person shooting the same load, it is easier for the gun to accelerate the lithsome person in reverse, further decreasing the felt recoil because of the length of time involved.
All quite academic, because all we really need to know is, yes they work, and do you like how they look?
