When picking the best seasons, as a fan, it's impossible to not let emotion get involved, especially since these comparisons are truly an academic exercise -- there's not definitive way to determine what football teams were better, especially when some of those teams played decades apart in world's that were very different. And when you get into the best half dozen seasons, it becomes difficult to see separation between them.
The three seasons below share very little in common, though 1979 and 1983 are close to each other in time. But they do share this in common: they were great seasons, with flaws, yes, but part of the best seasons in school history.
6. 1979
5. 2006
4. 1983
Criteria
Part 1: Nos. 40-36
Part 2: Nos. 35-31
Part 3: Nos. 30-26
Part 4: Nos. 25-21
Part 5: Nos. 20-16
Part 6: Nos. 15-13
Part 7: Nos. 12-10
Part 8: Nos. 9-7
6. 1979
Coach: LaVell Edwards
Record: 11-1
Ranking: 13th in the AP poll, 12th in the coaches' poll
Bowl: 38-37 loss to Indiana in the Holiday Bowl
Point Differential per game: 26.75
Opp. Winning %: .516
SRS: 18.13
What you didn't know: Marc Wilson was the WAC Offensive Player of the Year in 1979, leading the nation in passing yards with 3,720. In 2011, 11 QBs surpassed that number.
Summary
Could BYU's national championship have come 5 years earlier? The 1979 Cougars entered the Holiday Bowl an undefeated 11-0, a favorite to beat the 4th best team out of the Big Ten, 7-4 Indiana.
Despite an undefeated resume, the answer was no. Alabama was undefeated and very, very good. USC finished 2nd in the country, with only a tie keeping them from national title consideration. And there were five 1-loss teams ahead of BYU (including traditional powers Ohio State and Oklahoma). But they could have, in beating Indiana, finished in the top 5, which only two teams in BYU history have done (1984 and 1996).
Marc Wilson was the catalyst on this team, the nation's leading passer. He completed nearly 60% of his passes. Besides Wilson, the Cougars had 11 other players make First-Team All-WAC. It was to that point the greatest season in BYU history.
So what keeps this 1-loss season out of the top 5? Two related things. First, the Cougars beat only one above-average team in 1979, Texas A&M (6-5).* Second, the loss was to Indiana (8-4), a good team, but not a great one. They were in the middle of the pack for a Big Ten that was very top heavy that season.
* You might look at Texas A&M's 6-5 record and think the Aggies were not a very good team. They came into the season ranked No. 14 and would lose to the following teams (with Sports-Reference.com computer rankings in parenthesis): BYU (10), Baylor (20), Texas Tech (39), Houston (8), and Arkansas (6). Three losses to the top 10, and they also beat Texas (6). This was a very good team, despite the 5 losses. And the Cougars beat them in College Station. Wow.
But that shouldn't take anything away from this season. The offense was tremendous (40+ points a game, 4th best offense since 1972) and the defense gave up less than two touchdowns a game (3rd best PPG defense since 1972). This was a complete team, and many of the players who were important on this team would produce in 1980 and beyond.
BYU won 11 games in-a-row this season, the longest such streak in school history to that point. The 1979 team was a great team, and by my accounting, the sixth best team of the past 40 years.
5. 2006
Coach: Bronco Mendenhall
Record: 11-2
Ranking: 16th in the AP poll, 15th in the coaches' poll, 19th in the final BCS standings (done before the bowl game)
Bowl: 38-8 win over Oregon in the Las Vegas Bowl
Point Differential per game: 22.08
Opp. Winning %: .469
SRS: 15.21
What you didn't know: In the past 40 years, only three BYU teams have improved by 5 or more wins from the season before: 1996, 2001 and 2006. After 1996, the Cougars would average less than 8 wins per season the next three years. After 2001, the Cougars would average less than 5 wins per season over the next three years. The 2006 Cougars would sustain their success, averaging more than 10 wins over the next three seasons.
Summary
Bronco Mendenhall came into 2006 without massive external expectations. 2005 had been a decent season, with an offense that was better than any Gary Crowton had coached since cooking with LaVell's groceries in 2001. But the defense had given up almost 30 points a game, and fans were hopeful that the defensive-minded Mendenhall could fix a unit that hadn't held opponent to less than 20 points a game in more than 10 years.
And boy did the defense improve. Senior LB Cameron Jensen was named First Team All-MWC with a team-leading 107 tackles and 3 INTs. Junior Bryan Kehl, who had played sparingly in 2002 and 2005, added 70 tackles, including 9 for loss. And a freshman DL named Jan Jorgensen would tie for the team lead with 5 sacks. Jorgensen would go on to get 14 sacks the next season, and be named MWC Defensive Player of the Year as a senior in 2009.
The offense was almost identical statistically to Robert Anae's 2005 offense, led by senior QB John Beck, who was in his third year as a starter. He turned in his best season of his career, with almost 3900 yards passing and 32 TDs. His biggest weapon was fellow senior Curtis Brown, who had almost 1600 all-purpose yards and led the team in receptions. Jonny Harline did not just catch one of the most famous passes in BYU history, but also led the team with 935 yards receiving and 12 TDs.
The season began disastrously, as the veteran Cougars dropped two of their first three, one at Arizona and another at Boston College. It seemed, at that point, that another season of mediocrity was inevitable.
But the season turned on Sept. 28, 2006, when BYU stunned then No. 17 TCU 31-17 in Fort Worth. The defense, though not statistically spectacular, made great, timely plays, and Beck would play flawlessly: 321 yards on 23-of-37 passing and 3 TDs. It would be the second win of a 10-game winning streak that culminated with a thrashing of Oregon in the Las Vegas Bowl.
When you're talking about the best five seasons in BYU history, you have to nitpick. The biggest flaw of this team is losing to a mediocre Arizona team to start the season. The loss at Boston College is forgivable. Traveled east, played a good Eagles team (finished ranked 20th). But they should have beat the Wildcats, who finished 6-6 (though they did beat ranked Washington State and Cal teams later in the season). And besides BC and TCU, BYU didn't play any other really good teams.
But the positives from this season are enormous. A return to national prominence for the Cougars, after a collection of four very forgettable seasons. A victory over TCU. A conference championship. And, of course, an unforgettable comeback win against Utah with the infamous Beck-to-Harline TD pass with zero ticks remaining.
An unblemished season? Hardly, but it was a special season, and the best of Bronco's seven seasons at the helm. And it was good enough to be the 5th best season of the past 40 years.
4. 1983
Coach: LaVell Edwards
Record: 11-1
Ranking: 7th in the AP poll, 7th in the coaches' poll
Bowl: 21-17 win over Missouri in the Holiday Bowl
Point Differential per game: 21.05
Opp. Winning %: .514
SRS: 15.42
What you didn't know: From 1982 to 1983, Steve Young decreased from 18 to 10 INTs, and that was in 62 more attempts. He also increased his passing yards by more than 800, his passing touchdowns by 15 (from 18 to 33), and his YPA from 8.4 to 9.1.
Summary
As is not uncommon on this list, a loss on the road to a non-conference foe was the season's big blemish. In this case, the loss was to Baylor (7-4-1), a 40-36 slugfest in which the teams combined for more than 900 yards in total offense.
First Team All-American QB Steve Young had a terrific game against the Bears, with 351 yards passing and 143 yards rushing. He would go on to not lose another game and have one of the greatest seasons in college football history: 3900 yards passing, 33 touchdown passes, 71% pass completions, and 444 yards rushing and 8 rushing TDs. Young was joined on the offense by fellow All-American Gordon Hudson, a TE who caught 44 passes for 596 yards in just 8 games.
The defense that season was decent, allowing 20 points per game, but maybe should have been better with standouts like LB Todd Shell and DB Kyle Morrell. And that's especially true when you factor in that the Cougars did not play a top 20 team that season (as measured by the rankings at Sports-Reference.com).
The team gets credit for defeating three top 30-type teams in Air Force (10-2), UCLA (7-4) and Missouri (7-5). The UCLA and Air Force wins came on the road, and the Missouri win came in the Holiday Bowl, a tough 21-17 victory in which Steve Young was held to 7 yards rushing and was intercepted three times.
This is one of the best offensive teams BYU has ever had. The 42 points per game make it the third highest scoring offense in BYU history, behind the 1980 and 2001 squads. And this offensive output was produced in a season with a better schedule than either of those teams, and with a unique QB who created the standard of throw-first-but-then-destroy-with-the-legs QB that has only been matched by a few in college football history.
The defense, though, was pretty average by BYU standards (ranked 18th in the past 40 seasons), and the one loss, though it was to a Big 8 team, was to a pretty mediocre Big 8 team.
In the end, it was a terrific season with a incredible performance by one of the best athletes to ever wear the Cougar blue. And it was good enough for 4th on this list.