Petrino confirmed the news through a statement Tuesday afternoon (via ArkansasNews.com):
"I want to thank Willy Robinson for his role in helping our defense, which he leaves in better shape than when he arrived. I have the utmost respect for Willy Robinson as an individual who wants the best for the young men he coaches. I give Willy credit for his part in the building process the last four years and wish him future success."
Despite finishing the season 10-2, Arkansas struggled on defense all year. The Razorbacks finished 51st in the FBS in total defense and ninth in the SEC. Robinson's defense was seen as a point of weakness for the Hogs in three of his four seasons at the helm.
Robinson is the third coach to leave the Arkansas staff this week. Offensive coordinator Garrick McGee recently accepted the UAB Blazers head coaching position and special teams coach John L. Smith left to become the head coach at Weber State.
Petrino did not say who will run the defense for Arkansas in the upcoming Cotton Bowl.
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