The way I see it it works independently to the 4 rider picks and is like picking a 5th rider only it's a group of riders.
Out of the groups, which one do you think will score the most above the prediction?
If you think Emil and Artem will score, say, 20 points between them (maybe 16 and 4) you'll pick up 10 points on top of your 4 rider picks.
That's the only way I see it working. What other ways do you see?