The college football playoffs are definitely the best way to determine a champ. This is a method that has been successfully used for many years. Eliminating teams based on the fact that they have lost is really the only accurate way to determine a champ. Anything else would just not work.
Throughout the year the plays that happen are more important then the final one. It is all about the consistency and sometimes in the playoffs certain teams get lucky and win however that is not a reason good enough to call them champions. In this point of view - best way to know is to have playoffs throughout the year and measure the quality level in a distribute manner.