This year has taken a toll on Kubiak, 55, and his family.
Kubiak left the team for a week in October and missed a Thursday night game in San Diego for what the team called a "complex migraine condition." Back in 2013, when Kubiak was coaching the Houston Texans, he suffered a mini-stroke during a game and had to be rushed to the hospital.
The move might come as a surprise to many around the league, but there have been whispers throughout the year that Kubiak's family wanted him to leave coaching and move to their retirement ranch in Texas.
Both Kubiak and general manager John Elway, his former Broncos teammate, believed it was going to be a long and prosperous return.
Instead, Kubiak is expected to step down as Broncos coach after Sunday's regular-season finale against the Oakland Raiders.