The largely theoretical performance increase you might get with Tanner when it comes to passing the ball does not overcome the far less theoretical performance decrease you would get with Tanner when it comes to running the ball.

Taysom's ability to run, whether it be on a scramble or a called run or zone-read play is far greater than Tanner's. That's a fact. The supposed jump in passing performance you might get with Tanner over Taysom doesn't overcome the actual running performance you definitely get with Taysom over Tanner.