For starters, there's plenty of developed depth on this team at almost every position. The offensive line is stocked decently, and the skill position players are veterans who are ready to play.
Our junior and senior players come from classes that have decent talent. It's not as if we're stuck with Tregg Duerson-level players that few FBS schools wanted.
Also, Ian Book has actual game experience under his belt, having survived a somewhat shaky start against UNC, and pulling our bacon out of the fire against an excellent LSU defense. With more reps with the first team this spring, and a better understanding about how to play in real time, I see no reason why he wouldn't be at least a serviceable player, should Wimbush go down or be pulled.
He has decent enough footspeed to pose a reasonable running threat, and has good enough arm strength and accuracy to stretch the field.