User blog comment:Zilla4444/Less Randomness: Critchance/Critdamage; Wriggles;...Remake/@comment-5196742-20120617191423/@comment-5196742-20120617192014

I present all this as a consideration to the old mastery that gave 4% critical strike chance for essentially free and also unlocked extra damage from crits, which was pretty much standard for all AD carry build outs for late-game damage increase. The bottom line issue, however, was that 4%, totally random chance to crit (And the added damage) would win and lose lanes for people.

Imagine striking a crit during laning right out of nowhere. Enemy laner takes almost 250 free damage and is now forced to back, if he doesn't die outright from what is decidedly a "lucky crit".