Simple handicap here: this is the biggest game of Purdy’s life and the Niners want to minimize his mistakes. You can run against the Chiefs and the Niners have a great run game. Kyle Shanahan’s excessive pass play calling probably cost the Falcons the win against the Patriots back when he was their offensive coordinator. Kyle Shanahan’s dad won two Super Bowls through an effective run game (even with John Elway as his QB). Put all that together and the Niners want the ball in McCaffrey’s and Deebo’s hands and not Purdy’s.