Comparing recommended trinkets from AMR and more generic numbers from bloodmallet (SimCraft with generic profile) I noticed that Scars is ranked pretty low for AMR. Some random looking around lead me to this:
if StatRating(Haste) >= StatRating(Versatility) and StatRating(Haste) >= StatRating(CriticalStrike) and StatRating(Haste) >= StatRating(Mastery)
Is this the actual item logic used? If so that cannot be right as it seems to say that you only get 1 of the 4 buffs and nothing about the final effects of the final fifth rune. As far as I understand it, you get each buff (tertiary stat) when you apply the rune. Just you also get the debuff.