if you have a progressive LR the shock moves a larger percentage of the shock stroke compare to the associated wheel travel (in%) towards to the end of the stroke. Moving the wheel the same amount of travel the rebound forces have to be higher towards to the end of the stroke because more oil has to be moved through the rebound ports compare to the beginning of the stroke - that's the advantage of a progressive LR compare the progressive spring rate when you look towards rebound (means bit slower deeper in travel, more lively on top)- I assume...