You’re right. The 2nd and 3rd stringers were abysmal, and the starters that were left melted. Sitake basically said as much and made it a point of emphasis to try and build depth and work with the individual players who weren’t ready that game.
The thing is that regardless sometimes individual players have to go through the fire to come out better on the other side. Players like John Beck went very good when they were inexperienced either.