And as far as "good" teams are concerned, I categorized them as teams that won 8+ games.
2005
Loss - Boston College - 3 pts
Loss - TCU - 50 pts
Loss - Notre Dame - 23 pts
Loss - California - 28 pts
2006
Win - Tulsa - 49 pts
Loss - Boston College - 23 pts
Win - TCU - 32 pts
Win - Utah - 33 pts
2007
Loss - Tulsa - 47 pts
Win - Air Force - 31 pts
Win - New Mexico - 31 pts
Win - TCU - 27 pts
Win - Utah - 17 pts
2008
Loss - TCU - 7 pts
Win - Air Force - 38 pts
Loss - Utah - 25 pts
Loss - Arizona - 21 pts
2009
Win - Oklahoma - 14 pts
Loss - TCU - 7 pts
Win - Air force - 38 pts
Win - Utah - 26 pts
Win - Oregon St. - 44 pts
2010
L - Air Force - 14 pts
L - Florida St. - 10 pts
L - Nevada - 13 pts
W - SDSU - 24 pts
L - TCU - 3 pts
L - Utah - 16 pts
Overall, that's a record of 13-15 vs. teams that won 8+ games over that time span. In those games, BYU averaged 24.7 points. In 4 of the 15 losses, BYU scored enough points that those losses could have been attributed to poor defensive play and not poor offensive play, IMO.
Against teams that won 9+ games over that time span, we went 6-13 and averaged 21.1 points.
Against teams that won 10+ games over that span, we went 2-10 and averaged 21.4 points.
It seems to me that overall, the line between teams that we could regularly beat and those that we struggled with was around 9 games. We were 4-3 vs. teams w/ 9 wins over Anae's time here. We were 2-10 against 10+ win teams, and 50-8 vs. teams with 8 or fewer wins.
From 2006-2009 (removing Anae's 1st year on the job and his last year when the entire team was in disarray), we went 12-6 vs. teams that won 8+ games and averaged 28.2 ppg. We went 5-5 vs. teams that won 9+ games and averaged 24.4 ppg in those games. We went 2-5 vs. teams that won 10+ games and averaged 23.6 points vs. them.
The conclusions I get from this are as follow:
The better the opponent BYU played, the more BYU tended to struggle against them (as can be expected).
BYU had extremely good success in beating teams with 8 or fewer wins, and decent success when playing 9-win teams during this time span. The area that BYU struggled in was in playing teams with 10+ wins on the year.
Even with the struggles against 10+ win teams, BYU's offense wasn't terrible in these games on average. You've got to remember that TCU from 2008-2010 had one of the top defenses in the nation and most people struggled to score against them. Same thing could be said for Utah during that time span to a lesser extent.