The Colts finished the season with an 8-9 record and second place in the AFC South. Indy's defence ranked 29th in the league and 24th in points per game.
"I'm appreciative of Gus and the commitment he made to the Colts," said head coach Shane Steichen. "He is a man of great character, and I have the utmost respect for him. I felt like we needed to move in a different direction. I wish Gus and his family all the best moving forward."
The Colts ranked in the bottom 10 for defence in each of the three years Bradley was the defensive coordinator. But the now former Colts DC takes all the blame.
"The overall performance (in Week 17) was embarrassing and as a leader, it's my responsibility for our overall play and I take that responsibility," said Bradley before the regular-season finale this past weekend.
Bradley joins a long list of growing coaches succumbing to the infamous Black Monday. The Bengals fired defensive coordinator Lou Anarumo, Seattle fired offensive coordinator Ryan Grubb, and the Jacksonville Jaguars did the same to head coach Doug Pederson.