Players, coaches and other officials cast their votes on Adam Simpson's replacement, but Petrie was torn between wanting the captaincy and feeling immodest if he nominated himself.
Instead, he left the form blank and approached senior coach Dean Laidley to let him know that he'd sat it out.
"I didn't actually vote for anyone," he confirmed. "I was kind of a bit unsure on what to do.
"I was tossing up whether to put my own name down there but, at the same time, I didn't want to seem a bit self-indulged.
"I guess I use the analogy that Barack Obama didn't vote for John McCain in the last election in the States, did he? At the end of the day, I thought it was best to leave it blank and let the others decide."
Laidley acknowledged that Harvey had received a compelling show of support from his teammates, which ultimately endorsed the final decision.
"I thought he was a bit more of a chance than I was," Petrie said. "Your captain doesn't have to be your best player but I think your captain needs to be a player that performs consistently over four years, five years. Brent's done that.
"I think my form's been good over the last few years but he's had a lot more consistency over a longer period of time. I think that's why he got it in the end.
"[I'm] very excited for Brent and excited for myself with what lies ahead," he added.
"He's taught me a bit over time because I was lucky enough to live with him for a couple of years – in my second and third years – so pretty important years for a footballer to get a good grounding."
Petrie, 26, says he and Harvey are relieved the three-week waiting game is over and understands that injury or the eventual retirement of the veteran midfielder would thrust his name forth.
"I'll be carrying a baseball bat now, full-time, just in case – so I can kneecap him to get the top job," he joked.
"He'll be around for another three years you'd think. Hopefully by then we've got other emerging and potential captains to challenge me if I was to be in that position [again]. It would be a worry if it was an easy decision when that next time comes."
Petrie's appointment re-visits some familiar territory; he played out this season as part of the club's leadership group but struggled as a deputy vice-captain in 2004 and 2005.
With 154 games to his name and the best year of his career to build on, Petrie now sees the reasons behind that experience.
"I think back then it was a lot different with there still being 15, 16 senior players above me," he said.
"I probably stopped worrying about my performance as much and possibly tried to become this good leader, when all I needed to do was keep performing as a footballer on-field.
"People look back and always ask me this question about what happened three or four years into my career when I got the deputy vice-captain, but I gained positives out of it in what I've learnt and what I can apply to the group from now on."
