The production of gedolei hador as a gauge of the quality of a Yeshiva would be very misleading especially since many gedolim (possibly even most) did not spend most of their learning years in Yeshiva. We might even be able to say gedolim achieved what they did despite the Yeshiva system not because of it.
Think
Chazon Ish
Rav Moshe Feinstein
Rav Elyashiv
Of course, they had Rabbeim and did shimush by previous gedolim. But their greatness was not achieved in Yeshiva