Assuming BYU wins their six easier games (including what is predicted to be decent USU & N Illinois teams), BYU will need to go at least 3-3 against the tougher portion of their schedule.

BYU historically has done poorly against P5 teams (I believe their winning percentage is about 40% over the last 30 years) and very poor against good P5 teams (those with winning records) on the road. It can be argued that the best three BYU teams in the last 25 years are the 1996 team, the 2006 team, and the 2009 team. These teams went a combined 0-3 in true road games vs P5 teams, 1-4 in regular season games, and 4-4 overall. While a small sample size, these top teams only went .500 against P5 competion (and a giant 0-fer on the road where BYU plays 5 of their 6 toughest games). For comparison, BYU is 13-22 against P5 teams since going Indy.

I don't believe it is much of a stretch to say that these best BYU teams would struggle to go 3-3 against the likes of Arizona, Cal, Wisconsin, Washington, Boise & Utah. Personally I'd say that Washington & Wisconsin are almost guaranteed losses (1 road win against a top 10 team in school history) and argue that historically BYU would split the other 4 games (ending up 8-4).

My point is just that even the best teams we've had would likely struggle with this schedule (at least how it looks now). I expect that Utah & Boise will finish in the top 25 this year and Washington & Wisconsin will finish in the top 10. I expect that Arizona will be ranked at some point this year and I've seen predictions of Cal winning 7-8 games and making a bowl. Typically speaking, BYU doesn't do well in these types of games and expecting BYU to win even 2-3 isn't realistic. Hopefully I'll be able to do some more research on this soon.