It says in Sanhedrin Daf 24a מאי בבל א"ר יוחנן בלולה במקרא בלולה במשנה בלולה בתלמוד This is very interesting that the statement is being made by R' Yochanan. He was from the first generation of Amoroim in Eretz Yisrael (Someone not even from Bavel and far from the time when the Talmud was completed) and from his Beis Medresh came Talmud Yerushalmi? What shaychas does he have to make such a statement about Talmud Bavli (when certainly the same could be said about Talmud Yerushalmi). Although perhaps only a "historical" question it's still a little interesting why the gemorah is quoted this b'shem R' Yochanan.
If you look carefully at the Gemara it doesn't really say that.
R. Yochanan is talking about Babylon, or more specifically the Torah scholars there. There doesn't seem to be an indication that he is referring to the Babylonian Talmud. R. Yirmiah (second generation Babylonian Amora), on the other hand, applies R. Yochanan's teaching to the Babylonian Talmud (though even in his day it wasn't a finished product).