At Rosh Hashanah 19b, the Gemara raises a b'raisa quoting Rabbi Yehuda HaNasi (aka "Rebbe") -- the editor of the Mishna -- to counter the opinion of the anonymous Tanna quoted in the previous Mishna without refutation. I understand that an anonymous Mishna is usually a teaching of Rabbi Meir. But I'm confused that if Rebbe had a problem with the particular view of Rabbi Meir, why didn't he raise it himself in the Mishna and cite the Tanna he learned it from? It would seem to me that the fact that the Mishna does not include any refutation is evidence enough that either Rebbe is not the true author of the teaching in the B'raisa or, otherwise, he determined that the opinion he put into the Mishna was, ultimately, the end of the matter and no debate was necessary. What is the correct way to analyze this and other similar cases?