Other then the Death of Jason what would you say the definitive biggest Failure is Batman's career?
Letting all those people die because he wouldn't kill The Joker. Then there was that other time he let all those people die because he wouldn't kill The Joker. Oh and that other time where those people were killed by The Joker because Batman had previously allowed him to live.
Not doing anything about Arkham having the security of a bounce house. Letting a robin, his son and his parents die. Getting manhandled by Bane and turrning a common criminal into one of the most dangerous person alive(also not letting Joker get killed or executed).
He was still Batman deep inside and if batman/superman taught us anything, it's that a child version of batman could beat up muggers.
I was joking about him failing to save his parents life though.