Then again, we also know that the same man who rammed a lance through a crusader's body that it extended "a cubit" outside the OTHER layer (basically skewered him back to front - bonus WTF moment, the crusader survived it) also failed to penetrate a frankish mail in another lance charge, so there was a clear difference in mail quality in use, if not simply vagaries of realRNG (it's early, I don't feel like looking up the name - Usamah something, and since I went through several books yesterday when I skimmed over that one can't drop the source, but shouldn't be difficult to find).