In PvP all the damage numbers you see on the enemy from your hits are always far far smaller than what the tooltip says, or what you see in PvE.
A Wrecking Blow that absolutely Wrecks mobs outside of Cyrodil, hardly does half of that damage inside Cyrodil.
Doesn't that mean that penetration alone is the single most important thing in PvP?
Even if you don't increase your damage dramatically with high damage sets, and just focus on you penetration. And manage to penetrate around 90% of the damage of your simple tool tip, that would do wonders.
So why bother wearing high damage sets.
Many would say that a sharp trait and champion points in penetration etc are enough. But are they? Cause it doesn't to be the case.