The man himself offered an explanation to South Carolina fans in a letter to the editor in The State:
After six games, we were 2-4 with two blow-outs by Georgia and LSU. We were behind at halftime against UCF (a team that went 0-12 this year). We were definitely going in the wrong direction. I felt that I was doing a lousy job as head coach and a change would help our team become more competitive.
Spurrier noted that he left a $3 million buyout on the table, saving the university money, and he praised interim head coach Shawn Elliott for changing the attitude and improving the enthusiasm and effort of the Gamecocks. South Carolina was just 1-5 under Elliott, but that included one-score losses to Tennessee, Texas A&M and Clemson.
In addressing the critics who suggested that he quit on the team, Spurrier suggested that his actions were actually for his players' benefit:
I did not want a "Spurrier Farewell Tour." The players deserve to be the story of each game. Also, it would have prevented Shawn Elliott, a coach that has loved the South Carolina Gamecocks his whole life, from getting the shot to be the interim head coach, with the possibility of becoming the Head Coach here.
In general, Spurrier spoke in favor of coaching change:
When a coach gets fired, the change is often good and helpful to the team. Miami was 4-3 when Al Golden was fired, and the interim head coach went 4-1. Randy Edsall was 2-4 at Maryland when fired and his replacement got the team playing better. Clay Helton, the interim coach at the other USC, was recently named head coach as they went 5-2 under his watch.
As for the question of whether he is retired or interested in coaching again, Spurrier said that he might consider volunteering at a high school, but that his "head coaching career is done." He also thanked Gamecock fans and the university for the opportunity.
South Carolina has yet to name its new head coach, but you can stay on top of the search with SB Nation's coach rumor tracker here.