The next week Wisconsin was ranked #10.
Now, I don't know what LSU will be ranked this year and Wisky has more name recognition to get some better votes, but our game against LSU is a defacto home game for the Tigers. So a win could very easily jump BYU into the top 15.
Add in a win against (most likely) a top 10~12 Wisky team a week after also beating Utah, and I would definitely say BYU is top 5~7 in the polls with a 6-0 record.