Wow. Hard to remember the last time a guy screwed up the greatest opportunity in his professional life as quickly as did Sam Allardyce.

A year ago, he was an unemployed English soccer coach of middling reputation whose claim to celebrity, as far as it went, was “never being relegated” — a reputation he burnished last season by taking over the Sunderland club in October and steering a bad team out of relegation.

That rescue job, as well as England’s disastrous Euro 2016 tournament, which led to the resignation of coach Roy Hodgson, left a door open for the England job, generally considered to be the pinnacle of coaching, for Englishmen.

“Big Sam” got the job after a groundswell of support, much of it from journalists who liked his distinctly English style (direct and physical). Through the 2018 World Cup at 3 million pounds ($3.9 million) per year.

And only 67 days and one match after he was appointed he has resigned under pressure from the English Football Association after several compromising comments were caught on camera by investigative journalists working for the English newspaper The Daily Telegraph.

The newspaper was doing work on rumors of corruption in English soccer and published the story under the headline: “England manager Sam Allardyce for sale”.

Oh, Big Sam!

I like the guy, and what he stood for — on the pitch, anyway. A sort of big, bluff, straight-talking everyman who beat the odds and ended up at the top of England’s coaching ladder.

But he had to go because he showed that he was open to helping strangers “get around” FA rules pertaining to third-party ownership of players … as well as being prepared to take 400,000 pounds for making four trips to East Asia to talk to prospective investors in soccer players to give them advice for beating those rules.

It was spectacularly lame and perhaps illegal, and will be mentioned in the first paragraph of his obituary someday.

A chance to lead England to the 2018 World Cup, a chance to remain on afterward, a chance to take a nation desperate for World Cup success deep into the tournament … he threw it all away for what certainly appears to be avaricious reasons.

The story broke this morning in the Telegraph, and before the night was over, Allardyce was out, saying “I recognize I made some comments which have caused embarrassment” to the English FA.

To say the least.

It is fair to wonder why Allardyce and his agent took a meeting with some self-described Asian businessmen and, furthermore, than he sat there and told relative strangers how easy it is to work around the rules subscribed to by his bosses at the FA.

It is the sense of a little guy having some so far … and then throwing it away that is vaguely haunting.

The FA may discipline Allardyce, but he already has the punishment that hurts most — a reputation in ruins, a career derailed by his own greed and stupidity, all of it out there for anyone to watch. Hard to imagine any upper-level England team will take him on as coach. No TV work, either, for guys who get caught doing what Allardyce did.

Poor Big Sam.

Stupid, Stupid Big Sam.