Missing Etruscan onsets

This time, a much shorter post about the implications of Cyprian Syncope on Etruscan and about gaps in the expected available onset possibilities. If I've defined this Pre-Etruscan syncope properly, then it's curious that Etruscan lacks some expected clusters that could not have been reason to trigger stress shift to the first syllable. As I said before, wholesale onset deletion is unlikely to have happened to deal with impending invalid clusters since this would surely overload the vocabulary with a deluge of monosyllabic homophones which would in turn undoubtedly trigger tonogenesis like in Chinese in order to compensate with this imagined "lexical condensation". (But there's no evidence for tones in Etruscan so we aren't going there.)

I now have 1800 entries with over 4300 word forms in my database so I expect to find ample stuff when I search for words in Etruscan starting with pr-. Yet what does my simple search yield? I have only 11 headings starting with this onset! Six of them are names of either Italic or Greek origin (Prastina, Prisina, Priiamne, Prumaθe, Prumaθina and Prusilna). Of the remaining words (besides the one mystery term prezu I have trouble assigning a value and origin to), pruχu 'pitcher', pruχuna 'of the pitcher', prumaθś 'great-grandson' and prunta ~ frunta 'augur of lightning') are all Greek or Latin loanwords (cf. πρόχους, pronepos and βροντή). This same pattern happens when I search for pl- , seeing likewise only 11 terms consisting of many names and few words, all non-native terms. Why should this be so? What's so exotic about this onset cluster in a language with ample terms starting with #tr or #sr?!

We might invent a rule that *pR- (R = resonant) was somehow avoided in Proto-Cyprian by its aforementioned stress shift rule while *tR- and *sR- were allowed but I wince at the irregularity in that. Yet if the cluster survived into the post-Cyprian era, it suggests one possible thing: word-initial clusters of the form *pR were regularly simplified in Pre-Etruscan by deleting *p. I must remind myself to investigate this pattern further.


UPDATE

15 Oct 2010: I changed "Yet if the cluster survived into the post-Cyprian era, it suggests one thing" to something less absolute: "Yet if the cluster survived into the post-Cyprian era, it suggests one possible thing". Afterall we must rationally acknowledge other logical possibilities that may not be considered such as, perhaps, a general softening of *pR to *fR (although I have only five headings thus far in #fR making that particular idea impractical).