AS US secretary of defence Donald Rumsfeld mused back in 2002, there are "known knowns" and "known unknowns". 

But the ones to most worry about are the "unknown unknowns". According to Rumsfeld, the unknown unknowns are "the ones we don’t know we don’t know … the difficult ones". 

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When it comes to the 2020 AFL season, everything seems to reside in the unknown unknowns category, the latest exhibit being Bomber Conor McKenna testing positive to COVID-19 and forcing the postponement of his team's match against Melbourne. 

On Sunday night, no one attached to the AFL or Essendon Football Club was in a position to confidently predict what happens next in the chain of events sparked by McKenna's result. 

There was one known known, though – the people with whom McKenna lives, his brother and his brother's partner, had tested negative to coronavirus. Which is clearly good news on every level. 

There was also on Sunday night very strong hope that a worst-case scenario would not involve the entire Bombers playing list to be isolated for 14 days along with McKenna. 

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There was a feeling that a worst-case outcome would have a total of eight Bombers – McKenna and seven others he had been in "close contact" while they trained indoors – would be unavailable for selection for that period. But again, attempting to predict what the Victorian Department of Health and Human Services rules on this matter, as it attempts to fend off a feared second wave of COVID-19 infections, is far from being a subject to be placed in a "known known" category. 

Obviously, the best case result would be for McKenna to be the only Bomber to be forced to miss matches. 

Late on Sunday night, Essendon officials were still locked in phone and video hook-ups in an attempt to ensure that that be the case, and to mitigate all other spin-off damage. 

All the club's players and staff will be tested for COVID-19 on Monday morning.

McKenna had been told on the weekend to treat his dealings with the DHHS with full respect and honesty – to reveal his every known movement in the lead-up to his positive test, to not hide or dismiss any possible detail. 

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He has admitted to attending multiple open-house inspections, but social distancing protocols around such occasions are known to be extremely strict.

Even if eight Bombers are forced to isolate, the club's match against Carlton next Saturday will be played.

The postponed Melbourne game will be played later in the year. At this stage, and like everything else in 2020 even it too is subject to alteration, that is the only known known. 

Another questionable decision by Roo

As thousands of individuals and businesses suffer through the COVID-19 pandemic, a group of young men representing a football club in its 10th year of AFL life are breathing life into not just their own careers but the Australian football code in a historically problematic region of Australia. 

The Gold Coast Suns are the great AFL beneficiary of the coronavirus crisis. 

While effectively "hosting" the four clubs from WA and SA, they have exploded into form, with wins against the Eagles and Crows since the resumption of the 2020 season.

The No.1 national draft pick from last year, Matt Rowell, was best afield for a second consecutive week. Ben King kicked three goals, Touk Miller continued his progress, and Hugh Greenwood, the ex-Crow dubbed too old and slow by Adelaide football director Mark Ricciuto, racked up 13 tackles. 

Post match, Greenwood tweeted: "If only I were younger and quicker @markricciuto". It was a clever response to an unfair and damning public assessment. 

I was critical of Ricciuto in a column on AFL.com.au for his scathing public commentary about Greenwood and other Crows players who had chosen to exit the club, called for him to stand down from the club's board.

He's a very good person, Ricciuto, and wants nothing but the best for his beloved Crows. But he's been the club's football director during its worst moments in its 30-year AFL life. And while he attempted to be nothing but playful in responding to Greenwood on social media on Sunday night, his judgement in doing so was, yet again, questionable. Like so many other decisions made by the Crows since the 2017 Grand Final. And Greenwood then 'owned' him with another Tweet. 

Poor Matty Nicks, the first-year Crows coach. Right now he could do without a footy director potting ex players who couldn’t get out of his joint quick enough.  

Simmo needs to change his ways

West Coast coach Adam Simpson is justified in publicly bemoaning his club's plight. Being stuck in a hub on the Gold Coast in order to allow the 2020 AFL season be restarted is far from ideal. 

But it's a terrible look for a coach. And it's not surprising his team has lost the two matches it has played while in that hub, to Gold Coast in round two and to Brisbane on Saturday night. 

Simpson should be making noises privately and not publicly. Another West Coast official – CEO Trevor Nisbett or footy department boss Craig Vozzo – should have been doing the on-record and on-camera media rounds relating to the valid unfairness of the Eagles' plight. 

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Simpson is as footy-smart as they come, and it was a surprise to seem him complain so publicly. But as of Monday, he needs to change his ways and inject some energy into his group, and refrain from the woe-is-us attitude. 

Games are scheduled in south-east Queensland against Port Adelaide and Richmond in the next two weeks. Losses in both would be catastrophic, given there is a likelihood that at least one more game, and possibly two, will need to be played by the Eagles in Queensland before they get to return to WA. 

A new clear leader from the 2019 draft crop

The 2019 NAB AFL Rising Star award, over time, may stack up as the best ever. 

Sam Walsh won from Connor Rozee, Sydney Stack and Bailey Smith, with Ben King, Cam Zurhaar, Nick Blakey and Tarryn Thomas among the other nominees. 

It's obviously highly subjective, but I reckon if you added the three matches of 2020 to the assessment timeframe, Smith would be a clear leader. 

He has played 26 of a possible 26 matches since he was drafted, and looks more at home with every quarter of football.

In a match his team the Western Bulldogs just had to win last Friday night against GWS in order to keep alive the season, Smith was as crucial as anyone. He doesn't turn 20 until December. Can only imagine how good he will be when he's 24.