He wore yellow in both 2016 and 2018.Well its not about the quantity its about the quality of the wins, isn‘t it?
Since the two race in the modern cycling era, I see no reason why the two shouldn't be compared and Pogačar's palmares is already really close to Sagan's after just 4 years as a pro.
Sagan had a career of paradoxes. His three consecutive World titles were legendary and the 7 green jersies at the Tour was also something amazing but I just find a bit disappointing than he never wore the yellow jersey in the Tour and more important than that only won two monuments, even though he still has a small chance of finally winning MSR this year (should have tried LBL in his early years too). But I think he correctly recognised that his best days on the road are over and want to have some fun in the MTB. Wishing him all the best.