Crowd Calendar vs. Fastpass Availability

Magic Kingdom on January 23rd, 2017 is predicted at a 6.
Magic Kingdom on January 25th, 2017 is predicted at a 2.

However, if I look at Fastpass Availability for the Seven Dwarves Mine Train on these two dates, there are more Fastpasses available on the 23rd. That seems contrary to the crowd predictions, and makes me question their accuracy. Can anyone give me any insight?

Sometimes when they are expecting higher crowds, they offer more FPP+ for some attractions. That may be it.

The same is happening to me. Day 12/31 has much more fastpass available than 1/3. Maybe that’s right, they offer more fastpass on the more crowded days. One other reason would be that only a minority of people mark fastpass in advance, and the vast majority of people mark fastpass inside the park. So what influences the crowd of the park is how many people are willing to go to the park on that especific day (holidays, weekends, mondays) and not how many people marked fastpass in advance.