FORT WORTH, Texas—TCU and football coach Gary Patterson mutually agreed to immediately part ways Sunday before the completion of his 21st season. The announcement came a day after the Horned Frogs (3–5, 1–4 Big 12) lost 31–12 at Kansas State, Patterson’s alma mater. It was their fifth loss in six games, and they are 21–22 overall since the start of 2018. Patterson leaves TCU with a 181–79 record, including an undefeated 13–0 season in 2010 that was capped by a Rose Bowl victory. He was the second-longest tenured FBS coach, trailing only Iowa coach Kirk Ferentz, who is in his 23rd season. TCU athletic director Jeremiah Donati said he and school chancellor Victor Boschini met Sunday with the 61-year-old Patterson “and mutually agreed that the time has come for a new voice and leadership” in the football program. While responding in a text message that it was “correct” that he …