That's because your evaluation method is flawed. This isn't fantasy football where there are no negative points for giving the ball away, and you don't get more points for running the ball.
You can't win if you turn the ball over to the other team. Brissett doesn't do that. Fields passes less than just about everyone and throws interceptions and fumbles like the ball is burning his hands.
The most important stat in football is points, the second most important stat is turnovers, because it most correlates to points.