prior to BSU, the game in which he clearly wasn't playing well and the game in which he should have been pulled.

WSU....played well.
Weber....played well....broke back
Utah.....played ok by BYU vs Utah standards. Better stats than Hill 2013
BSU.....played terrible, substituted for Hill
Hawaii....didn't play
USU....didn't play
Oregon State....played ok in the only game that year the defense collapsed
Notre Dame....played ok against #2 team in the nation. Better stats than Hill had in 2013 against a weaker ND team.
Georgia Tech....threw a pic 6 but otherwise played well
Idaho....played very well....but...Idaho
SJSU....played not-so-good....lots of yard, poor completion percentage....reinjured
NMSU.....didn't play

Edit: You may be thinking of the bowl game. Lark was struggling badly and BYU had Nelson come in for 2 plays. He threw a Pic and went back to the bench.