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Every Big Ten West title scenario, explained

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Here are the possible outcomes, and how likely they are by S&P+.

NCAA Football: Notre Dame at Northwestern Mike DiNovo-USA TODAY Sports

If you’ve been following Northwestern football closely, you know that thanks to Iowa’s loss to Purdue last week the Wildcats only need to win two out of their last three games to guarantee that they make the Big Ten Championship. But several other scenarios are in play as well. Here is every Big Ten West possibility, from the perspective of a Northwestern fan.

A few disclaimers before I jump into things: all accompanying probabilities are via win expectancy from Bill Connelly’s S&P+. The metric is not especially bullish on the ‘Cats, especially compared to their divisional foes: they are currently slotted in at 68th, while Iowa sits at 29th, Purdue is ranked 25th, and Wisconsin is all the way up at 13th. Also, to create each conditional probability I treated each game as an independent event. They almost certainly are not, but that assumption is what I had to make for these calculations to be conceivable.

For reference:

The official 2018 Big Ten Football divisional tiebreakers.

Bill Connelly’s S&P+ stat profiles, where I took my win expectancy data from.

Northwestern wins if:

Without help

  • They win out (9.1%)
  • They win 2 of 3 (40%)

With help

Win Tiebreakers Easily, Iowa Eliminated

  • NU wins 1 of 3 and each of Iowa, Purdue, and Wisconsin get at least a loss somehow (10+1.9= 11.9%)

This scenario would put the Wildcats in a three way tie with Purdue and Wisconsin, where they would immediately advance via the first tiebreaker, having gone 2-0 against the Boilermakers and Badgers in the regular season. It also includes the possibility of a two-way tie with each team, where Northwestern would again win each tiebreaker. Or, it puts the Wildcats alone in front. No matter which way it goes, the 6-6 Wildcats would advance.

  • NU wins 1 of 3, Iowa wins out, and Purdue and Wisconsin each lose exactly once (4.8%)

This puts the Wildcats in a more complicated four-way tie with Iowa, Purdue and Wisconsin. Due to Iowa having lost to both Purdue and Wisconsin, regardless of whether they beat Northwestern, they will have a losing record against the other three tied teams. Therefore, they, along with the loser of Purdue-Wisconsin, who will be in the same boat, will be eliminated. Northwestern would then advance over the winner of Purdue-Wisconsin either by having beaten all three teams in the group or by virtue of their head-to-head win over that team.

Win three way ties by eliminating Iowa, after division record bypassed

  • NU beats only Illinois or Minnesota and Iowa wins out, Purdue beats Wisconsin and Indiana but loses to Minnesota, Wisconsin loses to exactly one of Penn State and Minnesota and loses to Purdue (1.1+0.2=1.3%)

Here, Northwestern would be in a three-way tie with Iowa and Purdue. The teams have identical records against each other and would finish with identical records of 4-2 in divisional play, bypassing the second tiebreaker. But by virtue of beating the team, in Wisconsin, who would be alone in fourth in this scenario (Illinois must lose to Iowa for the Hawkeyes to win out), Northwestern and Purdue would advance ahead of Iowa in the third tiebreaker. Then things revert to head-to-head, and Northwestern advances over Purdue.

  • NU beats only Illinois or Minnesota and Iowa wins out, Purdue beats Minnesota and Indiana but loses to Wisconsin, Wisconsin loses to both Penn State and Minnesota and beats Purdue (0.5%)

This scenario plays out the same way as the above, but with Northwestern being the only team in the top three to beat Wisconsin and therefore advancing immediately.

  • NU beats only Illinois or Minnesota and Iowa wins out, Purdue loses to Wisconsin and either Minnesota or Indiana, Wisconsin loses to Minnesota but beats Penn State and Purdue (0.2+0.1=0.3%)

This scenario plays out the same as the first in this category but with Wisconsin and Purdue flipped.

  • NU beats only Illinois or Minnesota and Iowa wins out, Purdue loses to Minnesota and Indiana but beats Wisconsin, Wisconsin beats Penn State and Minnesota but loses to Purdue (0.3%)

This plays out the same as the second scenario in this category but with Wisconsin and Purdue flipped.

Win three way tie by conference winning percentage of non-divisional opponents

  • NU beats only Illinois and Iowa wins out, Purdue loses out, Wisconsin beats Penn State and Purdue but loses to Minnesota (Can also flip Purdue and Wisconsin) (<0.08%)

This would create the same three-way tie as above but with the third tiebreaker bypassed, as every team would have split games against T-4th Wisconsin and Minnesota while beating Illinois and Nebraska. There are no East division teams that played any three of the potentially tied teams, so by my understanding of the tiebreakers, we would head to the fifth tiebreaker. Currently, the cumulative conference records of East division opponents shakes down like this:

  • Northwestern (MSU, Michigan, Rutgers): 10-8
  • Wisconsin (PSU, Michigan, Rutgers): 9-9
  • Purdue (OSU, MSU, Indiana): 10-8
  • Iowa (PSU, Maryland, Indiana): 7-11

(The odds of this scenario happening for any team is negligible, aka <0.1%)

Bear with me: E X T R E M E C H A O S NORTHWESTERN 5-7 IN BIG TEN CHAMPIONSHIP

  • NU loses out, Iowa loses to Nebraska, Illinois, or both, Purdue loses to Wisconsin and one or both of Minnesota and Indiana, Wisconsin beats Purdue but loses to Penn State and Minnesota, Illinois loses to Iowa or Nebraska (0.0244+0.0211+0.0190+0.0085+0.0073+0.0066+0.0047+0.0041+0.0037=0.0994=0.1%)
  • NU loses out, Iowa loses to Nebraska, Illinois, or both, Purdue beats Wisconsin but loses to both Minny and Indiana, Wisconsin loses to Purdue and one or both of Penn State and Minnesota, Illinois loses to Iowa or Nebraska (0.0440+0.0153+0.0085+0.0078+0.0061+0.0033+.0026+0.0015+0.0012=0.0903=0.1%)

Yes, Northwestern could possibly win the Big Ten West at 5-7. If the Wildcats lose out and Iowa, Purdue, and Wisconsin end up at 5-4 (Illinois winning out complicates things and is generally negligible), the same scenario as the 4-way tie at 6-3 would commence, with the Wildcats taking a head-to-head tiebreaker after two tied teams are eliminated. This also includes every possible two-way and three-way tie at 5-4 (again, not including Illinois).

Note: If you assume that Northwestern loses out, the odds of the above scenario are 2.1%. Also, the more exact odds of C H A O S are basically 1,897/1,000,000.

Chance Northwestern wins Big Ten West by S&P+: ~68.4%

Northwestern loses if:

Outright

Wisconsin, Purdue, or Iowa wins outright

  • NU loses out or goes 1 of 3 and Wisconsin wins out (10.5%) (Wisconsin wins West)
  • NU loses out or goes 1 of 3 and Purdue wins out (11.4%) (Purdue wins West)
  • NU loses out or goes 1 of 3 without beating Iowa and Iowa wins out while Purdue and Wisconsin both lose out or go 1 of 3 (2.3+0.5=2.8%) (Iowa wins West)
  • NU loses out, Iowa loses at least once, Purdue goes 2 of 3, Wisconsin wins 1 or fewer (0.5%) (Purdue wins West)
  • NU loses out, Iowa loses at least once, Wisconsin goes 2 of 3, Purdue wins 1 or fewer (0.5%) (Wisconsin wins West)

Tiebreakers among Wisconsin, Iowa, and Purdue

  • NU loses out, Iowa wins out, and Purdue and Wisconsin both go 2 of 3 with Wisconsin winning the head to head (0.7%) (Wisconsin wins West)
  • NU loses out, Iowa wins out, and Purdue and Wisconsin both go 2 of 3 with Purdue winning the head to head (0.4%) (Purdue wins West)

These are each three way ties in which the winner of Purdue-Wisconsin gets the tiebreaker by being 2-0 against the other two.

  • NU loses out, Iowa wins out, and Wisconsin wins 2 of 3 while Purdue wins 1 or less (0.8%) (Wisconsin wins West)
  • NU loses out, Iowa wins out, and Purdue wins 2 of 3 while Wisconsin wins 1 or less (0.8%) (Purdue wins West)

These are each head-to-head ties between Iowa and Purdue or Wisconsin, where Purdue or Wisconsin’s head-to-head win propels them through.

  • NU loses out, Iowa loses at least once, and Purdue and Wisconsin both go 2 of 3 with Wisconsin winning the head to head (0.5%) (Wisconsin wins West)
  • NU loses out, Iowa loses at least once, and Purdue and Wisconsin both go 2 of 3 with Purdue winning the head to head (0.3%) (Purdue wins West)

These are each head-to-head ties between Purdue and Wisconsin where the winner of their matchup goes through.

  • NU loses out, Iowa loses at least once, Purdue goes 2 of 3, Wisconsin wins 1 or less (0.5%) (Purdue wins West)
  • NU loses out, Iowa loses at least once, Wisconsin goes 2 of 3, Purdue wins 1 or less (0.5%) (Wisconsin wins West)

By Tiebreakers

  • NU goes 1 of 3 without beating Iowa and Iowa wins out while Wisconsin wins 2 of 3, losing to Penn State as their one loss, and Purdue goes 1 of 3 or winless (1.9%) (Wisconsin wins West)
  • NU goes 1 of 3 without beating Iowa and Iowa wins out while Purdue wins 2 of 3, losing to Indiana as their one loss, and Wisconsin goes 1 of 3 or winless (0.6%) (Purdue wins West)

These are three-way ties in which Wisconsin or Purdue get the second tiebreaker by virtue of a 5-1 record against the Big Ten West compared to Northwestern and Iowa’s identical 4-2 records.

Chance Purdue Wins Big Ten West by S&P+: ~14.0%

Chance Wisconsin Wins Big Ten West by S&P+: ~14.9%

Chance Iowa Wins Big Ten West by S&P+: ~2.8%

Adds to 100.1% thanks to rounding. Technically, Illinois has a <0.05% chance of winning in some C H A O S scenarios as well, and the negligible scenario could factor in at an infinitesimal level too.

One last note:

If Northwestern beats Iowa, odds it wins the Big Ten West:

Outright

-Win 1 or both remaining games (36.2+40.8+10.8= 87.8%)

Via Head-to-Head Tiebreaker

-Lose out, neither Purdue nor Wisconsin wins out (12.2- (2.7+2.5)=7.0%)

~94.8%


Ok, take a deep breath. We’ll know a whole lot more in a week.