Now lets do the math for the same dmg / item setup: So the new crit damage after the runes would be 245.5% for a standard champion, and (245.5%*.9) or 220.95% for Yasuo. If you do the math on these, Yasuo would be averaging 132 damage per hit, and other champion would be averaging 120. A different champ would have a 20% chance of doing 200 damage.
He would have a 40% chance of doing 180 damage. Let's say yasuo does 100 dmg on an attack and has an item that gives 20% crit chance. Although it's true he gets less value because his crits only do 180%, he actually gets a net gain of value because of the doubling of the chance to crit.
