D&C 35

Speaking of the Prophet Joseph Smith, the Lord told Sidney Rigdon -

"...I have sent forth the fulness of my gospel by the hand of my servant Joseph; and in weakness have I blessed him;"  (Doctrine and Covenants 35:17)

Then the Lord instructs Sidney -

"Wherefore, watch over him that his faith fail not, and it shall be given by the Comforter, the Holy Ghost, that knoweth all things."  (Doctrine and Covenants 35:19)

Sidney was older and had had much more experience in preaching and leading a congregation.  Obviously, there may be a tendency to be critical is such matters.  This might be the case of many in the Church that have had important callings and then have been released.  In all of this, the Lord declares that His servants may be weak and inexperienced.  But nonetheless we sustain and watch over or care for our leaders.