The widespread consensus is that if Brogan had converted that late one-on-one, a Dublin team surging with unstoppable momentum would have completed a logic-defying 10-point comeback to reach another All-Ireland SFC final.
And then, even against ominously in-form Donegal, who can tell what would have happened?
Instead, that equalising goal never materialised and the rest is history.
"It still haunts me," Dublin's go-to forward conceded, speaking in the aftermath of Saturday night's GAA/GPA All Stars football exhibition match at Gaelic Park, New York.
"But that's part and parcel of being a forward. I've had some great days when goals went in for me and you're always going to miss a few.
"It was an important one, but you live and learn from these things and hopefully, if I get into that position again, I'll put it away.
"I back myself - I went to put it into the bottom corner and the ball lifted a bit. Clarkey, in fairness, is like Peter Schmeichel coming out - he spreads himself like an eagle. He put the hand out and that was it. That's just the name of the game."
Brogan enjoyed a more productive goalscoring night in the Bronx, but his 2-1 tally (plus a hat-trick from marauding midfield team-mate Michael Darragh Macauley) wasn't enough to rescue the Pat Gilroy-managed 2011 All Stars. Instead, their 2012 counterparts, led by Donegal boss Jim McGuinness, took the plaudits on a 8-17 to 8-7 scoreline.
Saturday night, though, was all about putting on a free-scoring, tackle-free show for the Irish-American diaspora.
For Brogan & Co, the heavy-duty grind will start pretty soon as they attempt to recapture the magic formula of 2011. And they will do so, of course, under new management. The Gilroy reign is over; the Jim Gavin era is all set to begin.
The 2010 Footballer of the Year said he's looking forward to the "new voice" that Gavin will bring to the Dublin dressing-room.
"We weren't a million miles off it this year and we had a great year the year before, so I'm sure there shouldn't be too much that has to change.
"He has a lot to work with and I'd say he's looking forward to getting involved," Brogan suggested.
"I never really met the guy only just to say 'hello'. I'm looking forward to seeing what he thinks about football, the style he plays and so on. I know he played some lovely football with the under-21s - lovely free-flowing football."
Slightly at variance with his earlier assertion that Dublin weren't "a million miles off it", Brogan believes they never found their best form in 2012 until it was too late.
"It was hugely disappointing because I don't think we ever really got out of the blocks at all," he reflected.
"The last 20 minutes against Mayo was the only time we played any sort of football, and it was a little bit too late. If we had another 10 minutes we might have caught them and won the game, but we ran out of time."
It all means that Donegal, not Dublin, are now faced with the ultimate challenge of defending Sam Maguire. For over two decades it has proven beyond every county bar Kerry (in 2007), but Brogan still sees Donegal as the ones to watch in the New Year.
"They're setting the standard. You could see in 2011 that they were starting out with the machine that won the All-Ireland this year," he pointed out.
"They are the team to beat and hopefully we can keep an eye on what they're doing during the league, so we can pick up a thing or two and take them on.
"It would be nice to compete for the league because it's something none of us have. It's a huge goal for any footballer.
"The league is very closely correlated to All-Ireland success, so if you can do well in that you're in good stead for the summer. We're going to try to take that league title if we can."
The St Oliver Plunkett's/Eoghan Ruadh clubman signed off with a parting 'thank you' to Pat Gilroy, who managed Brogan for the last time on Saturday night.
"He put so much into it and Yvonne, his wife, and his business have been brilliant because they gave him the time he needed to put in and bring us to the holy grail.
"We have the utmost respect for him and I wouldn't be the footballer I am today only for him," he concluded.