This is all you need to know about the quarterback competition going into the 49ers’ preseason game against the Broncos. Even though he won’t play, Colin Kaepernick is the front-runner to be the Niners’ starting quarterback if he’s healthy and wants the job. Why? Because Blaine Gabbert is Blaine Gabbert. And Gabbert always has a problem with his arm slot. More on that in a moment.