Don't you love how FBS is a special little outlier where all of the corporate interests (bowls, regular season and postseason media rights holders, etc.) get to decide what is best for the sport?
The scarcity of spots in the CFP field is a manufactured dilemma.
Current field sizes...
FBS: 130 teams, 4 playoff spots (3.1%)
FCS: 125 teams, 24 playoff spots (19.2%)
Div. II: 173 teams, 28 playoff spots (16.2%)
Div. III: 250 teams, 32 playoff spots (12.8%)
To even get close to the level of the lowest proportional field size among the other divisions (D3), the FBS CFP field would need to be at least 16 teams (12.3% of FBS teams).
I don't think it should be 64, but Mike Leach is entertaining.
I agree teams that lose 3 or more games aren't the "best" under the current system (2007 notwithstanding). But there are also too few games overall and especially too few games between power teams from different conferences. Not saying this also isn't the case in other college football divisions where they play fewer regular season games, however, they all have much larger playoff field sizes and, save for a few upsets here and there, the perceived best teams will eventually meet.
The problem with the single-division setup is there are simply too many teams in P5 conferences now (other than the Big 12 where a true round robin schedule can occur). With 14 teams in the Big Ten, ACC, and SEC, assuming 9 conference games, you still miss 4 teams each regular season. If the SEC and ACC stay at 8 games, that's 5 of 13 teams they are missing in a given season. If enough teams miss each other at the top of the standings, I assume the tiebreaker would be record vs. common opponents or wins against the highest teams in the standings that all tied teams played when there is a lack of head-to-head results. I imagine opponent strength imbalance with be an even bigger gripe because the comparisons are being made league-wide as opposed to just within a division (with the teams emerging from each division getting a shot at the conference title). Who you miss in a given conference season just got more important.
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Here are the records and conference championship status of the teams that have won championships in each divisions over the last couple decades:
FBS MNC
2018: Alabama/Clemson (Winner will be 15-0; both CC)
2017: Alabama (13-1; Non-CC)
2016: Clemson (14-1; CC)
2015: Alabama (14-1; CC)
2014: Ohio State (14-1; CC)
2013: Florida State (14-0; CC)
2012: Alabama (13-1; CC)
2011: Alabama (12-1; Non-CC)
2010: Auburn (14-0; CC)
2009: Alabama (14-0; CC)
2008: Florida (13-1; CC)
2007: LSU (12-2; CC)
2006: Florida (13-1; CC)
2005: Texas (13-0; CC)
2004: USC (13-0; CC; 2 wins vacated)
2003 AP: USC (12-1; CC)
2003 Coaches: LSU (13-1; CC)
2002: Ohio State (14-0; co-CC with Iowa)
2001: Miami (12-0; CC)
2000: Oklahoma (13-0; CC)
Undefeated MNC: 9 times
1-loss MNC: 9 times (counting 2003 just once)
2-loss MNC: 1 time
Outright CC won MNC: 17 times
Co-CC won MNC: 1 time
Non-CC won MNC: 2 times
FCS Playoff Champion [FBS opponents in brackets]
2018: NDSU (would be 15-0; CC) or Eastern Washington (would be 13-2; CC [lost to Wazzu])
2017: NDSU (14-1; CC)
2016: James Madison (14-1; CC [lost to North Carolina])
2015: NDSU (13-2; co-CC with Illinois State)
2014: NDSU (15-1; co-CC with Illinois State [beat Iowa State])
2013: NDSU (15-0; CC [beat Kansas State])
2012: NDSU (14-1; CC [beat Colorado State])
2011: NDSU (14-1; co-CC with Northern Iowa [beat Minnesota])
2010: Eastern Washington (13-2; co-CC with Montana State [lost to Nevada])
2009: Villanova (14-1, co-CC with Richmond [beat Temple])
2008: Richmond (13-3, non-CC [finished
3rd in the CAA South][lost to Virginia])
2007: Appalachian State (13-2; co-CC with Wofford [beat Michigan])
2006: Appalachian State (14-1; CC [lost to NC State])
2005: Appalachian State (12-3; CC [lost to Kansas])
2004: James Madison (13-2; co-CC with William & Mary and Delaware [lost to West Virginia])
2003: Delaware (15-1; co-CC with UMass [beat Navy])
2002: Western Kentucky (12-3; co-CC with Western Illinois [lost to Kansas State])
2001: Montana (15-1; CC [lost to Hawaii])
2000: Georgia State (13-2; CC [lost to Georgia])
Undefeated Champion: 2 times
1-loss Champion: 9 times
2-loss Champion: 5 times
3-loss Champion: 3 times (all lost to an FBS team)
Outright CC won Playoff: 9 times
Co-CC won Playoff: 9 times
Non-CC won Playoff: 1 time
NOTE: The 2008 playoff champion finished THIRD in their division.
Div. II Playoff Champion
2018: Valdosta State (14-0; CC)
2017: Texas A&M–Commerce (14-1; non-CC)
2016: Northwest Missouri State (15-0; CC)
2015: Northwest Missouri State (15-0; CC)
2014: CSU–Pueblo (14-1; co-CC with Colorado Mines)
2013: Northwest Missouri State (15-0; CC)
2012: Valdosta State (12-2; non-CC)
2011: Pittsburg State (13-1; CC)
2010: Minnesota-Duluth (15-0; CC)
2009: Northwest Missouri State (14-1; CC)
2008: Minnesota-Duluth (15-0; CC)
2007: Valdosta State (13-1; non-CC)
2006: Grand Valley State (15-0; CC)
2005: Grand Valley State (14-0; CC)
2004: Valdosta State (13-1; CC)
2003: Grand Valley State (14-1; non-CC)
2002: Grand Valley State (14-0; CC)
2001: North Dakota (14-1; CC)
2000: Delta State (14-1; ??)
Undefeated Champion: 9 times
1-loss Champion: 9 times
2-loss Champion: 1 time
Outright CC won Playoff: 13 times
Co-CC won Playoff: 1 time
Non-CC won Playoff: 4 times
Uncertain CC status: 1 time (couldn't find 2000 data for Delta State's conference standing)
Div. III Playoff Champion
2018: Mary Hardin–Baylor (15-0; CC)
2017: Mount Union (15-0; CC)
2016: Mary Hardin–Baylor (15-0; CC)
2015: Mount Union (15-0; CC)
2014: Wisconsin-Whitewater (15-0; CC)
2013: Wisconsin-Whitewater (15-0; CC)
2012: Mount Union (15-0; CC)
2011: Wisconsin-Whitewater (15-0; CC)
2010: Wisconsin-Whitewater (15-0; CC)
2009: Wisconsin-Whitewater (15-0; CC)
2008: Mount Union (15-0; CC)
2007: Wisconsin-Whitewater (14-1; CC)
2006: Mount Union (15-0; CC)
2005: Mount Union (14-1; CC)
2004: Linfield (13-0; CC)
2003: Saint John's (MN) (14-0; CC)
2002: Mount Union (14-0; CC)
2001: Mount Union (14-0; CC)
2000: Mount Union (14-0; CC)
Undefeated Champion: 17 times
1-loss Champion: 2 times
2-loss Champion: 0 times
Outright CC won Playoff: 19 times
Co-CC won Playoff: 0 times
Non-CC won Playoff: 0 times
Crazy: In D3, the playoff champion was always an outright conference champion, and the playoff champion has been undefeated in 17 of the last 19 seasons.