The old formula was tentatively something like this:
IF Attacker's STR + DMG + Weapon type + Perk effect + Melee Skill factor + LCK > Target's END or AGI (whichever higher) + Melee Skill factor + Luck
THEN knockdown success
Anyhoo, nothing I've seen, heard or read so far makes me think that the perk system in Skyrim will handle things differently. A perk that gives a stun, knockdown, or other disable or effect would likely be given the same chance to proc regardless of the attacker or target. Without the old attributes, a hulking Nord would have the same chance to knockdown a troll as he would have to knock up..er down the local tavern wench. And the same Nord going head to head against a Bosmer with the same perk would be as likely to get knocked down as to knock the other down.
So I'm looking for suggestions to replace the old STR vs END (or STR or AGI, still undecided) contested roll I had planned. I suppose a check could be made against the health of the target, to reflect how hard he is to take down. But what "attribute" could replace the attacker's STR to determine his chance to succeed?
Also, this would be a whole lot harder if like in FO3 and NV, perks couldnt be attached to NPCs so here's hoping...