Per KFord preseason expectations, NIU had a basically-guaranteed win (99%) playing Western Illinois...and a basically-guaranteed loss playing Notre Dame (2%). So let's just look at those first two to get an idea of why NIU doesn't 'overachieve' as much by that metric.

Adding those two game together, NIU was expected to have 1.01 victories in the first two weeks. But by percentages you'd expect a 1.98% chance they win both, a 97.04% chance they win exactly one (almost certainly the Western Illinois game obviously) and a 0.98% chance they lose both.

Compare that to a team playing two toss-up 50/50 games, which means would only be expected to have 1.00 victories in two weeks. But by percentages there's a 25% shot they're 2-0, another 25% that they're 0-2 and 50% they're 1-1.

Which team is more surprising to see at 2-0? Definitely the former...even if the latter has 'overachieved' more