Not many teams have swapped starting quarterback for starting quarterback. It happened earlier this year, with the Rams giving up on Sam Bradford and the Eagles giving up on Nick Foles and both teams hoping that the guy the other team got rid of will be an upgrade over the guy each team got rid of.
In 1980, the Oilers had other plans. After losing to the Steelers two straight times in the AFC title game, Houston went all in in an effort to win it all, swapping 30-year-old quarterback Dan Pastorini to the Raiders for 34-year-old quarterback Ken Stabler.