My understanding (not an expert) is that it's a combination of less high jumps/falls because "wood chips hurt", and reduced long bone injuries for the jumps/fal

My understanding (not an expert) is that it's a combination of less high jumps/falls because "wood chips hurt", and reduced long bone injuries for the jumps/falls that due occur due to differences in the way the material responds to the impact. Wood chips slide and absorb some of the kinetic energy, while rubber matting (and probably rubber chips?) stay in place and rebound the energy back.