There's a fair number of pollsters not rating teams that have yet to play - being G5 and likely in the others receiving votes section to begin with, Boise can't deal with losing any potential voters.
On another note, this is why BYU is likely to drop this week regardless of result. Not ranking someone at all REALLY hurts them.
For example (in a simplified world where every pollster has the same order, just some skip over teams that haven't played) if you have 2 pollsters who rate Michigan #10 and one who refuses to rank them, that gives them 32 points.
Meanwhile, BYU has two voters who put them #15 and the other at #10 (due to Ohio St, Penn St, Oregon, Wisconsin and Michigan being unranked) and they now have 38 points.
Next week though, Michigan (in theory) gets all three #10 (48 points), and BYU gets all three voting them #15 (33 points) and that jumps them way ahead.
This also means it's going to be tough for Boise (or other G5 schools) to move up in the next few weeks