No one never makes mistakes, and BB/Peoli have made some -- Starks and Beisel come to mind. The real issue is not do you make mistakes, it's do you get things more right than wrong, do you learn from and not repeat mistakes, and do you get it right when you bet big.
By this standard, BB and Peoli have not been perfect or mistake-free, but they've done a lot of big stuff right.