I believe that Round Two of the NASCAR Playoffs is the most intense.  It has to do with expectations and perceptions. 

When you're a team like Jimmie Johnson, Kevin Harvick or Kyle Busch, you begin the year with expectations of running for the championship.  In other words, making the finals at Homestead.

For teams like that, making the Final Eight is a given.  And, that's where the pressure comes in.  To not make the Final Eight, no matter what kind of year they've had, would be seen as failure.  To finish 10th or 11th may only be a few spots lower than 7th or 8th, but in the world of perception, it's a gulf as wide as the Grand Canyon.

The First Round was about not getting into trouble, and letting the lesser teams get weeded out.  The Third Round is about moving your year from very good to championship level.  That leaves this round, and it's, in the very least, about not having your year considered mediocre.