The Falcons blew a 28-3 lead and lost 34-28 to New England in overtime.
“It’s as hard as anything I’ve gone through,” he said. “I remember every single play, and I will go over those for the rest of my life,” Shanahan said. “That’s kind of the life we live as coaches. It’s magnified in the Super Bowl, but it’s also that case in every game.”
In San Francisco, Shanahan and new general manager John Lynch received six-year contracts and a promise of patience from team ownership.
“(It) shows that (CEO Jed York) he’s willing to give you some time,” Shanahan said. “What I didn’t want to do was come here and make a bunch of decisions just trying to win to save ourselves right away. I want to win the first day to the last day. I’m going to do everything possible to do that. But, I also want to make the right decision for the organization. John wants to make the right decision for the organization.”
The 49ers have won just 15 games the past three years and hit rock bottom in 2016 with a 2-14 mark that matched the worst in franchise history.
Lynch will have control of the 90-man roster, the draft and free agency, while Shanahan has final say on the 53-man roster.
Shanahan said he is racing to put his staff together and only confirmed one hire in running backs coach Bobby Turner, who worked with Shanahan in Washington and Atlanta.
The Associated Press contributed to this article.