Mair, Codex Wallerstein, Fiore, Goliath, Hans Cynner, Marozzo, Vadi, the Solothurner Fechtbuch, Talhoffer, ect depict the dagger fight just the opposite of Silver. Other than showing a very very very few "long range" attacks, most all of the fights are grapples/weapon control that put one in a position to quickly stab, throw, break, or any combination of those. I don't think you and I disagreee with this, but I just wanted to be clear that Silver appears to be the exception. I shouldn't have referanced him earlier as his dagger fight appears to be more dualing oriented...and that's just not how I view the dagger fight
Jared, your observation that these sources depict a different kind of dagger fight than Silver is, I think, accurate. However, that does not make them contradictory to Silver. I have spend the majority of my training time on analyzing the techniques in all these sources (except for Mair and Goliath). In my analysis of these sources, they depict responses for different kinds of fights. You will not that almost without exception, these sources deal with defense against a committed attack, which is the manner in which you will most likely be assaulted with a knife on the street. In a committed attack, the attacker does not precede his major blow with a feint or some other distraction, but instead launches it from a standing stop with the intention that it land and kill. The defenses depicted in the majority of sources you mentioned revolve around addressing this concept.
One must also bear in mind the fact that the dagger techniques in these sources are intended for use in armored and unarmored situations, interchangably. Gladiatoria, for instance, depicts its dagger techniques using armored men, and those techniques are identical to those found in Fiore, the Codex, and Talhoffer.
Silver on the other hand does not address these concepts at all. He is concerned strictly with the dagger-to-dagger *duel* between unarmored men using double edged weapons of the kind prevailant in the late 1500s. These weapons could be used efficiently for both cutting and thrusting (which is not to say that earlier weapons had no edges and couldn't cut; they could). He supposes that both men have their weapons deployed at the ready, whereas in the knife assault typically one man has his weapon out and the other does not.
The short implistic answer, then, is that the sources you list depict techniques for combat, while Silver describes concepts for the duel.