Vedic sanskrit, as used by the Rig Veda was written word perfect over the course of Kaal (time). During the time of the Buddha, oral recitation of of doctrines and paradigms where the usual practise.
I can appreciate how one can read wikipedia and feel an expert, however in order to reject a theory or hypothesis, one must actually have an awareness (mindfully!) of what that hypothesis was.
The vedas, were not always categorised into 4 distinct components, this was not done until the time of Veda Vyas, which has been argued by Scholars to be 3rd millenia BCE. Again the vedic language or pre-classical sanskrit was later evolved to classical sanskrit later used in the puranas. This i can comprehend is what is causing you confusion.
I can appreciate that it is very easy to use the little sources out there, such as wiki as a framework to direct intellectual curiosities, however, one should also understand that the esoteric scholars at Haridar and Varansi, whom have studied the language in-depth will refute from arguing in such affairs, as to do so in an expression of ego and trapped in a web of delusion. I have read your other thread and actually find it amusing - like a scientist who practises evidence based medicine, one must be mindfully aware of where such sources have arisen, and any bias incorporated. Just because a language has evolved over time can not mean to deny the origin of the language, where the core structure has remained intact.
One must also appreciate that despite there being a grammatical difference between the early Rig vedic sanskrit, and the later upanishads - you should also be aware of even older recited sanskrit tantric verses, that have over time only been passed orally from guru to student. These verses, can not and will not be littered over wikipedia. The language and grammatical content of these are remarkably identical to the rig-vedic language you keep harping on about - i.e. sanskrit.
You observation is that since the language used in the Rig vedic sanskirt, is different grammatically to the Sanskrit used in later texts is true. However, to claim that 'Sanskrit' did not exist per se during the time of the Buddha is incorrect, and evidence points to the contrary. A proponent to my theory would be the chandi, in the markenda purana. The Rig Vedic hymn, the Ratri Suktam is a composite and integral part in the purana, however a customarily evaluation of the core sanskriti grammar used between the Vedic and puranic language supports that between this and the later added dyanams, that there is a subtle differences in the construct of the sentences. However both undeniably share a common structure, pronunciation and thus origin.
You claim the language of the Vedas were not Sanskrit - evidence please? Give me written examples and exact verses that support your theory. Please show me the difference in vocabulary and grammar between the vyas sanskriti and that of the rig vedas.
I mean do you even understand pali and Sanskrit? Or are you just echoing the opinions of others.
What i find comical is that you fail to see the most obvious: praciti and sanskriti. This again has significant esoteric levels of understanding consciousness.
I fail to find your subjective interpretations of a questionable series of wikipedia articles as actual evidence convincing - more like propaganda and dogma.
Vedic Sanskrit corpus - since you like to draw your opinions from wiki - you might want to to read this page:http://en.wikipedia.org/wiki/Vedas
Om mane padme hum