It cost the vice chairman and his son their jobs.
Polian told The Associated Press on Wednesday that not grooming a replacement for the injured Manning was the primary reason the Colts collapsed this season, going from Super Bowl contender to the league's worst record.
"I've always told the staff that our approach should be to hope for the best but plan for the worst, and I didn't do an adequate enough job of planning for the circumstances we were in," Polian said in a telephone interview. "It led to this catastrophe."
When asked if he was referring specifically to finding a backup for Manning, Polian said: "Yes."
It's the first time Polian has commented since he and his son, general manager Chris Polian, were fired Monday.
The longtime NFL executive revived the Colts' brand name in two seasons, turning a moribund organization into one of the league's model franchises. During Polian's 14-year tenure, the Colts won 143 regular-season games, eight division titles, two AFC crowns and the first Super Bowl championship in the Indianapolis era.
Even all that couldn't save Polian after a 2-14 record this season gave Indianapolis the No. 1 draft pick.
"I understand what the dynamics are. So when you have the kind of season we had, there's always some accountability, and that includes me," Polian said. "Was I surprised? No. The timing of it was a bit surprising but not the end result."
Does Polian believe Manning will play again next season after his third neck surgery last September?
"I don't know. I can't answer that," Polian said. "I recognize that's been a frustration for fans, for you people in the media, and I wish I could have given you more concrete answers, but I just don't know. I hope for his sake if he wants to play and the situation is right for him, that he can play."
Copyright 2012 by The Associated Press