Chryst, a former player and offensive coordinator for the Badgers, is 19-19 in three seasons with the Panthers.
No decision expected on coaching situation until Wednesday.
Defense dominated the day as Wisconsin shot just 34.8% from the field while the Phoenix made only 35.1% of their shots.
Jordan Fouse added 13 points and eight rebounds for the Phoenix (7-2).
A pinpoint passer with wide-receiver speed, Mariota came into his junior season as the favorite to win the 80th Heisman.
Along with the 17 points, Dekker grabbed five rebounds, had three assists and two blocks for Wisconsin (10-1).
Green Bay is coming off a road win at South Dakota State.
The Phoenix is coming off a big win at Miami.
Reports say Pitt coach Paul Chryst will become Wisconsin’s next head coach.
The junior becomes the third Badgers player to win the award.