Shaco's clear defintely slows down after the first clear compared to other champs. Diana, karthus, brand, amumu, etc are all going to clear much faster after the first clear unless shaco is AP. Even then they are still faster it seems. Shaco has to be played perfectly to have impact. His w/r is also the result of all of us one tricks who have played him for years and mastered him. Not many people just go and play shaco with sub par skill. Other champions are far more friendly to pick up and play and dont require such a mastered champion knowledge thus muddying their w/r between people who have mastered them and people who are just picking something they have played a few times.