Geonic input into Maseches Nazir

We started Maseches Nazir two days ago. Here is a link to a Daf Yomi shiur from Rabbi Aryeh Lebowitz. I'll quote him from the 2:30 mark until the 2:56 mark:

The Rishonim already point out that the leshonos of the gemara in maseches Nazir are different from the leshonos of gemaras throughout the rest of Shas. That there are a lot of places in Nazir where things seem to be abbreviated; they seem to be formulated differently that they are in the rest of Shas; and it seems to be that the reason is that in the time of the Geonim, they didn't learn maseches Nazir in yeshivos, and any sefer that wasn't learned that much, a lot of mistakes crept in because there wasn't that much learning of it going on, where they were able to correct the mistakes. You'll find a lot of girsaos that were changed, nuschaos there were changed, by some of the later Acharonim, because it wasn't really taken care of in the earlier generations, since maseches Nazir wasn't really learned so much.

In fact, in the Tiferes Yisrael, in Pirkei Avos, in the second perek of Pirkei Avos, he writes, ודרך אפשר, that it could be that Rav Ashi, when he was mesader the Talmud, didn't get to produce a Mahadura Shniyah [second, revised edition] of Maseches Nazir, that for each of the other masechtas, he wrote a Mahadura Kamma, a first edition, and then he corrected it and made a Mahadura Shniyah. Maseches Nazir, what he have, is a Mahadura Kamma. This is what Shas would have looked like if Rav Ashi didn't have the time to review all the other masechtos. That is what the Tiferes Yisrael suggests, at least as a ודרך אפש. 

The first paragraph indicates, from Rishonim, that there was general Geonim input into our masechtos, something less present or absent in Nazir, which accounts for the difference in style. Is this just entropy -- errors that crept in during the copying process that were not corrected? What then with the abbreviations, or different formulations? The Tiferes Yisrael, meanwhile, seems to be suggesting that there was less of a work-over by the Setama DeGemara, but since he assumes an entire closing of the Talmudic canon [chasimas haTalmud] by Ravina and Rav Ashi, he puts this as a lack of a Mahadura Shniya.

Another way of looking at it (though I don't know what they say particularly about Nazir) is as many modern academic scholars say, that the editing of Talmud, in terms of expansive or simplifying language, or even whole sections of Setama DeGamara, extended into the times of the Geonim. If so, lack of Savoraic and Geonic attention to the masechta, or focus of different Savoraim and Geonim, could lead to a very different style.