One man an offense doesn't make. - This statement is normally true, however Vince Young was the offense. The rushing attack depended on Young, the Passing attack depended on Young. Hell the defense, special teams and coaching staff depended on Young for the simple fact that he was the energy and spirit of UT. Young was to Texas as Michael Vick is to Atlanta, do they have talent surrounding him? Yes. Are they near the team with out him? Hell No.
Great you have 4 running backs who had 400 yard seasons, only one can touch the ball at a time and they will have a much harder time now that the D no longer has to worry about the double threat of Young.
National Championship teams who loose the foundation of their teams are rarely ranked number one come the next year, unless they have proven themselves constantly - Texas will be ranked in the top 5, but not number 1.