Last January, Case Keenum threw 20 incompletions, threw two picks, and threw away what felt like a Super Bowl in the cold of the NFC championship game in Philadelphia. The Minnesota Vikings saw their quarterback get outdueled by Eagles backup Nick Foles, dashing the dream of hosting the Super Bowl. Afterward, the franchise focused on a single thing – get a quarterback, just about any quarterback, at just about any price. All the other pieces were there, they believed. So they went out and got Kirk Cousins, for $84 million over three years, convincing him to come to Minnesota because...