The Book Switch Theory

[asteckley]

Which is fine for an object of this age, by the way. 

I don't know what this means. You seem to be saying it "by the way" in the sense that its uncertainty does not diminish it as evidence (for the standard provenance story, I presume?).  But of course, that is not true. The more uncertain any information is, the more it diminishes its value as supporting evidence -- regardless of what theory it is being used to support.

I would say that the Tepenec signature is good, solid evidence. This is a crucial factor that changes the reading of the diagram dramatically.

I would like to consider it stronger evidence than the other yellow boxes (and I intentionally separated it from the observations in the red-dashed box regarding the Kircher Letters).  But I can't see it as hard evidence, given the questions surrounding it.

1. It says—as near as modern technology can reveal—Jacobus de Tepenec.   But Wilfrid Voynich was the one who determined that the name actually refers to Jakub Hořčický (Jacobus Sinapius).  We don't know that. It is somewhat circular reasoning to say that it does. Wilfrid identified a person associated with Rudolph II who also happened to receive the de Tepenec title in 1608, and so considered him to be a plausible "owner" of the signature. That identification has then been widely accepted as true. (In fact, some have taken it as evidence that the VMS was indeed associated with Rudolph II -- thereby supporting the hearsay put forth by Marci.  But that's circular reasoning -- Wilfrid sought out a plausible candidate for the signature based on Marci's statement.)
   
2. It's been observed that the signature does not match that of Jakub Hořčický  (and, as usual, speculative explanations are put forth in order to account for that so as to continue to support the story.)
   

So it may indeed be true that the signature is that of Hořčický -- which would indeed put the VMS into the hands of -- if not the ownership of--  Hořčický sometime during or after 1608.  But it just can't be considered hard evidence. By contrast, the other items (in green boxes) all have multiple sources supporting their veracity—or, in the case of C14 dating, multiple tests combined with a very reliable scientific testing procedure.