Here is what Coach Callahan said at the Big Red Breakfest. The reason he put Beck 3rd on the depth chart is because he was afraid that what happened last year would happen this year. Last year after dailey threw 3 interceptions against Kansas, fans began chanting for Davis to come in and take over, but Callahan didn't do it. Then the next week, when we went down to Tech and Joe threw the interceptions, Callahan threw Davis in the game to show fans WHY he did not put davis in the week before. Callahan figured it was easier for Davis to swallow fans booing him on the road then being booed at home.
Beck is not ready yet and Callahan said so. He said he still has to grasp some parts of the offense. If you put beck second on the depth chart and Zac somehow begins to go downhill during a game, and fans start chanting for Beck to come in (since he would be the backup) and Beck somehow isn't ready and begins throwing interceptions like Davis did last year against Tech, Beck could possibly get crucified by fans and the Media about being overrated as a passer.
Callahan is protecting his player, plain and simple until Beck is ready