They were, as like said this was something which took place over centuries.
This is a quote from Ajayib Al-Dunya, 13th century.
Arran: No other site has as many Turks: they say there are a hundred thousand Turkish horsemen.
http://www.vostlit.info/Texts/rus11/Cudesa_2/frametext.htm
And this was only 13th century. It is well known that the migration of tribes continued well into 15th century.
What is a "Turkic mixture"? Are you saying that Turks were 100% Mongoloid? To have 10-15% "Mongoloid" admix doesn't means you are 10-15% Turkic, it means you are at least half of that. But there is no doubt that Oghuz Turks had mixed with Iranian populations even in Central Asia. And what he posted showed the same 10-15% for certain areas of Anatolia and whole of Azerbaijan.
What? How could they have "accepted" a language from nowhere? Their language are very distinct like said, unique, it is not Oghuz. It is older than Oghuz, and much more related to proto-Turkic aswell. I don't rule out mixing btw.
Sorry, I cannot read your link, since it is written in Russian. But, you accept that the current population of azerbaijan is a mixture. is it right?
If you accept it, we can settle on something. which would be that we are a separate ethnic group who are connected to both Turkic people and locals(Iranians).