[whswhs]

Suppose that I miss my Brawling roll by 2 and you miss your Dodge roll by 4. Is that interpreted as your having dodged into my blow, so I hit despite myself? Or do you play that a miss is still a miss?

In the former interpretation, combat will be over in fewer exchanges of blows, especially with less skilled combatants, as failed defenses will turn misses into hits. On the other hand, you'll have a defense roll for every attack roll, so that you'll be making rather more defense roll.

In the latter interpretation, you won't be making any added defense rolls, but you'll also be having less speedup, as missed blows won't turn into hits.

Either way, you'll have really nerfed defense. Consider: A typical competent (but not heroic) combatant will have Attack-12, but will have Dodge-9 (assuming Combat Reflexes). So an average attack will succeed by 1-2 points. To beat that, the foe has to succeed against Dodge-8 or -7. You've lowered the chance of Dodge working from 3/8 to 1/4 or even 1/6; that is, you've reduced its value by between a third and three-sevenths.