Tyler Bray believes that every rookie has something to prove. He may have more than most. But outside of Smith, their unquestioned starter, everything appears to be up in the air, and that means Bray with all the physical tools could have a shot at a backup job. Bray put up big numbers as a starter with the Vols, but questions about his maturity and some minor off-the-field incidents caused his stock to drop. He's been participating in the Chiefs' rookie minicamp that finishes up Sunday. The Chiefs traded their second-round pick and a conditional choice in next year's draft to acquire Alex Smith from the San Francisco 49ers. The former Tennessee quarterback left school a year early hoping he'd be chosen highly in the draft, given the relatively weak collection of college signal-callers coming out this year.