IF all things were equal for all teams (ie SOS, OL quality, WR quality, etc), I'd agree with you. Since they're not, the best way to evaluate the season will be at the end of the season once BYU's plays some of the easier teams on our schedule like most other teams have ALREADY played.
Btw, by ESPN's Total QB Rating (Total QBR) which takes into account more than just passing and includes opponent strength, Taysom is the 47th ranked QB in the nation.