Let's tease out this 'opinion as fact' thing a bit further.
Take this line from Hamilton's article:
In the Lions’ minds, the gutsy three-point loss to Sydney was a three-goal win. The QClash was the grand final.
That is clearly the writer's opinion, even though it's presented without any sort of qualifier.
Compare it to this line:
The Lions asked for feedback on their coach and received complaints about Justin Leppitsch’s personal skills.
That could be based on inside knowledge, but there aren't any specific details to make it deniable. So we can't be sure whether it's based on a credible source, or if Hamilton is presenting an opinion the same way he did above.
Then there's this:
It may eventuate that Leppitsch can’t coach. I have concerns that the Lions don’t put enough emphasis on the opposition in their planning.
Here Hamilton does make it clear that he's voicing an opinion. But we don't know what it's based on. Someone has possibly fed that back to him, but it's just as likely that it's his own observations from watching the team, which frankly are about as valid as the opinions of anyone here.
But because he peppers his articles with lines like this...
They sought expert advice from Hawthorn on how a coach wins back a playing group he had lost.
...that do provide specifics and therefore are more credible, an uncritical reader would be forgiven for accepting the whole thing as factually based, even though it is an opinion piece.