It was one of several questions O'Malley fielded from a group of about 4,400 midshipmen during the academy's Forrestal Lecture, which was established in 1970 and has featured prominent political leaders over the years.
"The biggest mistake I've made as a leader is continuing to believe that a person subordinate to me -- but in a critical leadership position -- would be able to get it together, right himself and resume his responsibilities on the ship, so to speak," O'Malley told about 4,400 midshipmen in Alumni Hall.
O'Malley, who didn't mention the person he was talking about, said he was "too patient with that, and I have tried to correct that by being much more focused on mission and understanding that, you know, I'm not running a summer camp here."
O'Malley also declined during an interview after the speech to say to whom he was referring.
O'Malley also answered a question about the HBO television show "The Wire," a gritty crime show that was based on and filmed in Baltimore, mostly while he was mayor. The student asked whether O'Malley believed the show had anything to offer about problems facing big cities.
"I tell you what: I can't stand 'The Wire,'" O'Malley said. "I can't stand 'The Wire.' I can't say that I've ever seen an entire episode of it. I watched enough of it to know that it did not portray the full picture of what Baltimore is all about as a city."
The governor then added that he supposed the show has value as an art form "to the extent that it can make us more sensitive to the sort of carnage and suffering that goes on in so many big American cities, especially around the issue of drugs and drug dealing.
"It's hard for me to believe that if the numbers of young Americans, mostly men, who are dying on our streets in these drug wars -- shooting each other in appalling numbers -- were young and poor and white that we would be as content with doing the level of things that we do and don't do to combat it, as we do when they're young and poor and black."
O'Malley added: "So I suppose for that reason 'The Wire' was probably a good thing that made us all think. I guess what I found disappointing about it was that its sort of cynicism about human nature."
O'Malley said that his time as mayor made him believe that there was "a lot more that unites us than divides us." He said investing in drug treatment and locking up "the most recidivist, hardened repeat offenders" demonstrated progress could be made.
"My knock on 'The Wire' is that it's just so darn cynical about human nature," O'Malley told the midshipmen, who applauded his answer. "People are not that hopeless. People are not that callous. People are not that selfish -- not the Baltimore that I served for eight years."
The academy's Forrestal Lecture has been given by prominent political, athletic and military leaders, including former Secretary of State Henry Kissinger, football coach Dick Vermeil and Supreme Court Justice Antonin Scalia.