Why is the sky blue? Why is water wet? At the end of the day, some things just are what they are....you can ask why, but then pass up the chance to enjoy the "what".
Honestly, I don't worry about the "whys" with Madden sliders...I plug in a value, watch what happens on the field....nothing more than that. Not trying to be snarky or anything...it's just my philosophy anymore.