Why is Yaakov sending Yehuda as a new Rosh Yeshiva? A lot of focus of answering this question is about Yehuda’s role or his difference from Yosef.
But a simple question – Yosef is already there. Why can’t he be a Rosh Yeshiva? He was Yaakov’s best student, he just proved that he remembers his Eglah learning. Maybe he sent the Eglah to demand his Rosh Yeshiva position, even. So, after irritating brothers by favoring Yosef, Yaakov is now sending a new Rosh Yeshiva risking offending Yosef.
pshat preferred.