I think people push their children in mold, or to go to x yeshiva like all their brothers/cousins/friends etc rather than actually find a good fit place.
Perhaps the yeshiva was just never his type. We all grow in different circumstances.
It’s really not a crazy question or a surprise.
Oftentimes we are somewhere we think were doing great but Hashem puts us somewhere else that is unexpected but we preform better in.