Tanner is a much better freshman qb than Taysom was, but that means nothing. It is about who will give byu the best chance of winning next year.
I feel senior Taysom likely gives is a better chance at winning next year. Maybe senior Tanner will be as good, or even better, as what I expect Taysom to be next year, but you play who will give you best chance of winning, not who have the best career averages