Just a few cents;
Crushthrough does not stun long enough to land a second overhead if you play your shielder right. Plenty of time to sidestep and slash the mauler.
Plenty of variants to the shielder, same as any class. 15/21 plays way different than 21/15; dashing with short pierce/blunt + light shield VS juggernaut with sword + huscarl. The former relies on getting behind the enemy by movement, the latter fits teamwork better due to the frequent 1-2 hit kills.
As for shielders being defensive, not even the mightiest 2her can consistenly face two to four enemies and emerge victorious without a single hp lost. Try it, it's fun.
And yes, if possible, the scoreboard would be sexier with a points column instead of a kdr, based on damage dealt/absorbed, horse kills and so on. Though I reckon if it was indeed feasible, it'd been done by now.