There is always the threat of injury to your starter. Like I said before, there are many out there (including one of the most recent articles by DL) that feel Bauserman could possibly leave the school to start elsewhere because he realizes he might not start here. He also thinks Guiton could be more fit to be a WR than QB, only in emergency cases.
You don't go through a season with only 2 or 3 QB's, one being average at best in Guiton. Injuries can hit, and if they hit us like they did Oregon last year, there goes the season.