Other than determining conf or div champions I’m not aware that conf or nonconference losses matter
It has an impact on both conference/division races and on the overall win-loss records because what to SEC (and ACC) teams do with their 4th non-conference game? (They usually play an FCS team).
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Looking at division races...
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Playing 8 conference games instead of 9 in 14-team leagues means 7 fewer guaranteed losses.
It also means a given team is only playing 8 of the other 13 teams in the conference (not that 9 of 13 is much better). This is a reason super conferences suck.
Playing just 8 conference games in 7-team divisions also means you get seasons like 2012 where neither division champion (Georgia and Alabama) played any of the top 3 in the other division:
EAST
Georgia 12-2/7-1: Crossovers were vs. Ole Miss (3-5, W 37-10) and at Auburn (0-8, W 38-0); Lost at #6 South Carolina 7-35, Won vs. #3 Florida 17-9 (neutral site); Never played ranked teams in consecutive weeks, played two over a three-game/four-week span.
Florida 11-2/7-1: Crossovers were vs. #4 LSU (6-2, W 14-6) and at Texas A&M (6-2, W 20-7); Won vs. #9 South Carolina 44-11, Lost vs. #12 Georgia 9-17 (neutral site); Played three ranked opponents in four-week span (none in true road games) and four in a six-week span.
South Carolina 11-2/6-2: Crossovers were at #9 LSU (6-2, L 21-23) and vs. Arkansas (2-6 W 38-0); Won vs. Georgia 35-7, Lost at Florida 11-44; played three Top 10 teams in consecutive weeks, including the last two on the road.
WEST
Alabama 13-1/7-1: Crossovers were at Missouri (2-6, W 42-10) and at Tennessee (1-7, W 44-13), strange that they were both on the road; Won at #5 LSU 21-17, Lost vs. #15 Texas A&M 24-29; played three ranked opponents in consecutive weeks.
LSU 10-3/6-2: Crossovers were at #10 Florida (7-1, L 6-14) and vs. #3 South Carolina (6-2, W 23-21); Won at Texas A&M 24-19, Lost vs. Alabama 17-21; played FIVE consecutive ranked opponents, including three Top-10 teams in four games.
Texas A&M 11-2/6-2: Crossovers were vs. #24 Florida (7-1, L 17-20) and vs. Missouri (2-6, W 59-29); Lost vs. #6 LSU 19-24, Won at Alabama 29-24, played back-to-back ranked opponents twice (four ranked opponents in five weeks).
Crossover Records
EAST
Georgia: 2-0 vs. a combined 3-13 (Ole Miss and Auburn).
Florida: 2-0 vs. a combined 12-4 (LSU and A&M).
South Carolina: 1-1 vs. a combined 8-8 (LSU and Arkansas).
1-1 against each other.
WEST
Alabama: 2-0 vs. a combined 3-13 (Missouri and Tennessee).
LSU: 1-1 vs. a combined 13-3 (Florida and South Carolina).
Texas A&M: 1-1 vs. a combined 9-7 (Florida and Missouri).
1-1 against each other.
I'm sure it's a coincidence that the division winners happened to play the weakest crossover schedules Incidentally, the #2 team in each division happened to play the #2 AND #3 team in the other division.
If South Carolina plays someone more beatable than LSU as a crossover, there's a potential for a 3-way tie in the east without changing any division game results.
If Alabama plays someone that could challenge them as a crossover, there's a potential for a 3-way tie in the west without changing any division game results.
I don't know what the tiebreakers are after head-to-head, probably division record and then common crossover opponents, then like the Big 12 in 2007 where they had to go to the BCS to break the Texas-Oklahoma-Texas Tech tie.
Additionally, while Georgia beat Florida head to head, Florida played #9 South Carolina the week before playing #12 Georgia, while Georgia played Kentucky (0-8) the week before they played Florida.
I know, it's easy to pick outliers because they stick out. But that is something both conferences have in common: potential for crossover imbalance determining the division champions via non-common opponents.
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Now moving to what teams do in non-conference scheduling...
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2018 Big Ten Non-Conference
Looks like everyone except for Illinois and Minnesota played at least one Power 5 team (or Notre Dame) in the non-conference (Wisconsin in a technical grey area playing independent BYU). Ohio State played two.
No team played more than 7 home games...
ILLINOIS (6H, 5A, 1N)
vs. Kent State
vs. Western Illinois (FCS)
vs. USF (neutral site)
INDIANA (7H, 5A)
at Florida International
vs. Virginia
vs. Ball State
IOWA (7H, 5A)
vs. Northern Illinois
vs. Iowa State
vs. Northern Iowa (FCS)
MARYLAND (7H, 5A)
vs. Texas
at Bowling Green
vs. Temple
MICHIGAN STATE (7H, 5A)
vs. Utah State
at Arizona State
vs. Central Michigan
MICHIGAN (7H, 5A)
at Notre Dame
vs. Western Michigan
vs. SMU
MINNESOTA (7H, 5A)
vs. New Mexico State
vs. Fresno State
vs. Miami (OH)
NEBRASKA (7H, 5A)
vs. Akron (scheduled, didn't happen and was replaced with Bethune-Cookman)
vs. Colorado
vs. Troy
NORTHWESTERN (7H, 5A)
vs. Duke
vs. Akron
vs. Notre Dame
OHIO STATE (7H, 4A, 1N)
vs. Oregon State
vs. TCU (neutral site)
vs. Tulane
PENN STATE (7H, 5A)
vs. Appalachian State
at Pitt
vs. Kent State
PURDUE (7H, 5A)
vs. Eastern Michigan
vs. Missouri
vs. Boston College
RUTGERS (7H, 5A)
vs. Texas State
at Kansas
vs. Buffalo
WISCONSIN (7H, 5A)
vs. Western Kentucky
vs. New Mexico
vs. BYU
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2018 SEC Non-Conference
Looks like everyone except for Arkansas played exactly one Power 5 team (or Notre Dame) in the non-conference.
No team played more than 7 home games...
ALABAMA (7H, 4A, 1N)
vs. Louisville (neutral site)
vs. Arkansas State
vs. Louisiana-Lafayette
vs. The Citadel (FCS)
ARKANSAS (7H, 4A, 1N)
vs. Eastern Illinois (FCS)
at Colorado State
vs. North Texas
vs. Tulsa
AUBURN (7H, 4A, 1N)
vs. Washington (neutral site)
vs. Alabama State (FCS)
vs. Southern Miss
vs. Liberty Fighting Turner Gills
FLORIDA (7H, 4A, 1N)
vs. Charleston Southern (FCS)
vs. Colorado State
vs. Idaho
at Florida State
GEORGIA (7H, 4A, 1N)
vs. Austin Peay (FCS)
vs. Middle Tennessee State
vs. UMass
vs. Georgia Tech
KENTUCKY (7H, 5A)
vs. Central Michigan
vs. Murray State (FCS)
vs. Middle Tennessee State
at Louisville
LSU (7H, 4A, 1N)
vs. Miami (FL) (neutral site)
vs. SE Louisiana (FCS)
vs. Louisiana Tech
vs. Rice
MISSISSIPPI STATE (7H, 5A)
vs. Stephen F. Austin (FCS)
at Kansas State
vs. Louisiana-Lafayette
vs. Louisiana Tech
MISSOURI (7H, 5A)
vs. UT-Martin (FCS)
vs. Wyoming
at Purdue
vs. Memphis
OLE MISS (7H, 4A, 1N)
vs. Texas Tech (neutral site)
vs. Southern Illinois (FCS)
vs. Kent State
vs. Louisiana-Monroe
SOUTH CAROLINA (7H, 5A)
vs. Coastal Carolina Fighting Joe Moglias
vs. Marshall
vs. Chattanooga (FCS)
at Clemson
TENNESSEE (7H, 4A, 1N)
vs. West Virginia (neutral site)
vs. East Tennessee State (FCS)
vs. UTEP
vs. Charlotte
TEXAS A&M (7H, 4A, 1N)
vs. Northwestern State (FCS)
vs. Clemson
vs. Louisiana-Monroe
vs. Alabama-Birmingham
VANDERBILT (7H, 5A, and someone at the league office must have it in for them with their conference road schedule: 3 straight and 4 in 5 games from 06 Oct to 10 Nov)
vs. Middle Tennessee State
vs. Nevada
at Notre Dame
vs. Tennessee Tech (FCS)
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Here's the tally...
2018 Scheduled Non-Conference Games: Power 5 (Home / Away / Neutral) / Group of 5 (Home/Away/Neutral) / FCS (Home / Away / Neutral)
BIG TEN: 14 (9 / 4 / 1) / 26 (23 / 2 / 1) / 2 (2 / 0 / 0)
SEC: 13 (2 / 6 / 5) / 29 (28 / 1 / 0) / 14 (14 / 0 / 0)
For the sake of accounting, I treated both BYU and Notre Dame as Power 5 teams. If you want to count BYU as a Group of 5, then here is the revised total...
BIG TEN: 13 (8 / 4 / 1) / 27 (24 / 2 / 1) / 2 (2 / 0 / 0)
SEC: 13 (2 / 6 / 5) / 29 (28 / 1 / 0) / 14 (14 / 0 / 0)
All scheduled games (Conference and Non-Conference, counting each conference's participation in a game as an entry)
BIG TEN: 140 / 26 / 2 (counting BYU as Power 5) or 139 / 27 / 2 (counting BYU as Group of 5)
SEC: 125 / 29 / 14
All Power 5 teams being equal on average (we know that's not true, obviously, but close probably enough in the aggregate), it shouldn't be a shock when the Big Ten averages 12-12.5 more losses league-wide than the SEC (or slightly less than one loss per team on average).
That accounts for league game SEC teams don't play (126 conference game entries for the Big Ten, 112 for the SEC), which are almost across the board replaced with FCS games (12) and Group of 5 games (2), not non-conference Power 5 games.