Does passion alone win Origin games? No.
Does talent and ability alone win Origin games? No.
Every series the teams are, talent and ability wise, extremely even. You can argue QLD has had an edge for at least 4 of the last 6 years because of the "spine", but as much of a revolving door the NSW spine has been, as players they've been every bit as talented as the QLD team.
And that dates back to the start of the concept in 1980.
So why has Queensland been so dominant? Is it passion? I think it is. And I don't mean passion as in yelling out Queenslander, or loving your state more, or any of the cliches that get associated with Origin fans (although there is no doubt QLD fans are more passionate about Origin than NSW fans...but that's another thread).
I agree with Big Pete. Passion is a blanket term for all the intangible qualities that lift performance. Commitment. Desperation. Motivation. Attitude. It's the qualities that make a player do things above and beyond what they do week in, week out in club football, under pressure, when it counts, for the entire 80 minutes of the game. Even Phil Gould says it. Nobody plays for 80 minutes with the same intensity, commitment, desperation and attitude as Queensland Origin teams do.
Look at how many Queenslanders who are relatively unspectacular club players lift to a new level at Origin. Adam Mogg. Josh Hannay. Craig Teevan. Brent Tate. Steve Price. Paul Bowman. They're guys who you'd look at club form and think "geez, they're not Origin standard". But put on a Maroon jersey and they grow another leg and perform at a level you just can't fathom.
I admit I have maroon tainted glasses so I may be unfair, but I can't think of any NSW players who fit that category. In a lot of cases, players who are excellent club players tend not to shine at Origin level and in fact look off the pace. That's not a talent issue. It's not an ability issue. It's something intangible.
I put it down to passion.