There is a fascinating piece of Rav Tzadok HaKohen ZTL of Lublin explaining why there are times when the Gadolim are of a lower level and the rest is of a higher level, and some times the other way around.
Why was it after Navuah ceased did the Chachmos haTorah of the Anshei Kenese haGdolah and Talmud emerge?
He basically explains that there is a concept that Dargos and Chachmoh is of Klal Yisrael as one, and some times it is as Idchei m’Kamei Gavra, the dargos are sort of condensed into a few, and there are times when all is spread out among all of Klal Yisrael.
See below link for more, he explains it and elaborates in other places as well (As of now, I do not remember where…)
http://www.hebrewbooks.org/pdfpager.aspx?req=14377&st=&pgnum=10