I noticed when I was at Shar Yashuv and the Mir in NY that success in Torah always seemed to depend on Fear of God. I can not really explain this now years later. It was not a matter of who was learning the most Musar. It was something else. In fact I recall that there seemed to be people who were overdoing it with the Musar thing --and that certainly did not help. But the people that had the most success in learning seemed to have a certain degree of fear of God that was a bit more than usual.

In any case, to me today it seems that the Musar yeshivas developed the right balance. Two short sessions in Musar every day and the rest of the day learning Gemara in depth.