Why does math show that TWF does more DPS than THF, but in-game experience doesn't?

Cop-out answer 1: The calculations are so complex that the math can't possibly be right.

Cop-out answer 2: In-game observations are always subjective, and people see what they want to see.

While both of these cop-out answers tend to have some kernel of truth, I suspect that the math isn't as far off as some people think, nor are game observations as colored as other people think. I think there is a better answer.

Glancing Blows hit multiple targets.

Well, duh! Tell us something we don't already know! But, the fact of the matter is, most modeling DPS calculations are only only calculating damage vs. a single target, but most empirical observations come from some combination of "how fast stuff dies" and "looking at the kill count", both of which give full weight to multiple-target damage (and tend to obscure points where there is only one "boss" remaining and the whole party is attacking it).

However, it was not until actually playing with some numbers that I realized how big this gap might be.

For the purposes of this thought experiment, I took two WF Frenzied Berserker 20's, a THF'er and a TWF'er, assuming the same equipment for both (TWF had Min II Khopeshes, THF had Min II Falchion), and damage-optimal feat and enhancement choices. Against a *single target*, the TWF Barb should be generating more DPS. However, against two or more targets, the THF Barb generates more DPS. That's right -- adding only a second target allows the heavy damage a FB III gets on glancing blows to catchup and pass the TWF.

Moreover, in cases with a good thick cluster of mobs, the THF Barb generates a *lot* more DPS. Against 5 targets, I came up with the THF Barb generating 62%(!) more DPS than the TWF barb. For the benefit of those who don't frequently run the numbers -- trust me, this is a *huge* gap. In fact, the THF Barb needs to only maintain an average of attacking 1.5 mobs to equal the TWF DPS output.

Now, to cut off some objections:

Q: But cforce, no-one knows the exact percentage of glancing blow effects. Doesn't this make your analysis invalid?
A: Nah, it doesn't turn out to make that big of a difference, since the base damage and vicious components are so much larger than the effects. I assumed a 30% chance on the base effect, but even going as high as a 60% chance only changes the glancing blow damage by about 5%. Qualitatively, the observations are still the same: less at one target, more at two targets, a *lot* more at five targets.

Q: Doesn't the THF-Twitch technique give you a lot more attacks?
A: I assumed a Madstoned THF Barbarian using twitch attacking can get 133-134 swings/minute, (or a hasted one got 126-127) but I don't have any video confirmation on these numbers yet. If someone can demonstrate a faster speed, by all means post a vid. For THF to be attacking fast enough to equal TWF on *one* target, it would need a madstoned-attack rate of about 144/minute.

Q: What if I don't use "twitch" THF technique?
A: Well, you're a lot further behind on a single target. I mean, a *lot* -- to the tune of 25%. But, here's the good news: you're still a little ahead of TWF on two targets, and you're *much* further ahead on 5 targets -- close to *double* the TWF rate. Regular THF fighting does get a lot more glancing blows than twitch THF in the new combat system, so the "twitch" method is only optimal against one or two targets, now.

Q: What if I'm not a FB?
A: Well, the same basic principle applies, although the upside is a lot lower. Still, multiple targets goes to the THF Kensai over a TWF Kensai as well -- just not by as much of a margin. This should come as a shock to no-one: THF FB is *way* ahead of the pack on multi-target damage.

OK, I've tried to lay this out as reasonably as possible, which can only mean: it's time for irrational the holy war to begin!!! Flame ON!