Nashville SC

Six-team group: advantage or disadvantage?

When it comes to the MLS is Back tournament, most people are excited to see and talk about real, live sporting events again. I am excited to play around with dumb spreadsheets. Also the soccer thing, but mostly the spreadsheets.

As we’ve known for several days, the tournament will consist of a group stage in which most of the groups have four members, but Group A is a six-team unit. As of yesterday, we know that Nashville SC is in that group. It’s clear that this is not a level playing field, necessarily, but is it a good thing or a bad thing for the teams in the larger group?

Rules of the competition

Per the literature distributed by Major League Soccer, the rules are as follows: the top two teams from each group automatically earn a berth into the knockout stages. The remaining four spots go to the best third-place finishers (in terms of points, though there are also other tiebreakers downstream) across the six groups.

The structure of the six-team group is also relevant here: it’s essentially two three-team mini-groups, but instead of playing the other two members of your mini-group, you play all three members of the opposite one.

MLS is Back Group A
Mini-Group 1 Mini-Group 2
Orlando City SC (A1) Inter Miami CF (A2)
Philadelphia Union (A4) New York City FC (A3)
Chicago Fire FC (A5) Nashville SC (A6)

If you’re in the column on the left, you play the three teams in the column on the right, and vice versa.

Theoretically this means a third-place team in Group A can have a perfect group stage with three wins (one of the mini-groups sweeps the other), though obviously that is not the expectation. What are the likely outcomes, then?

Crunching the numbers

Since there are nine total games in this group, each with three possible outcomes (“home” win, “away” win, draw), there are 19,683 total different permutations (3^9) for how the final table plays out. In the four-team groups, it’s much simpler: only six games – with three outcomes apiece – means only 729 different permutations.

What we’re most interested in here is how the numbers either benefit or damage the third-place teams, though: the top two teams control their own destinies, whereas the dynamics of different group sizes come into play for that “best third-place team” distinction.

Without further ado…

MLS is Back Group A
Third-place team points Number of outcomes Percentage
9 2 0.01%
7 126 0.64%
6 2,484 12.62%
5 3,987 20.26%
4 11,922 60.57%
3 1135 5.77%
2 27 0.14%

And what does it look like for the (much simpler) four-team groups?

MLS is Back Groups B-F
Third-place team points Number of outcomes Percentage
6 8 1.10%
5 4 0.55%
4 290 39.78%
3 273 37.45%
2 136 18.66%
1 18 2.47%

There’s a bit to unpack there. Let’s do it.

What it means

I’ll make one clarification before the math folks come after me: we’ll just assume each outcome is equally likely in all three games for the sake of using “outcome/n” interchangeably with “probability.” Obviously some teams are stronger or weaker than others in reality.

As you can see, it’s overwhelmingly likely that the third-place team in Group A has at least four points. It’s more likely than not (though not by a huge margin) that the third-place team in each of the other five groups fails to reach that number. “Four points” is a fairly safe threshold to advance, then*. That’s true regardless of the nature of the groups, but is a more likely bar to clear for the Group A teams.

*The probability that there are enough third-place teams from groups B-F with four points that a Group A team with that number would need tiebreakers or miss the knockout stage completely is 2.95%. I really wouldn’t sweat it, especially given they can still have the advantage of the tiebreakers.

Essentially, barring worst-case scenarios, a team from Group A is qualifying for the knockout stages by being the third-place finisher. Even with just three points – a scenario that happens less than 6% of the time – it’s reasonably safe to assume a good chance of advancing on tiebreakers.

From that perspective, if you think you’re one of the best three teams in Group A, you’re feeling good. A major downside, of course, is in the specifics: only third-place finishers are eligible, so that means fully half the teams in Group A can’t possibly advance to the knockout stages, even though the fourth-place finisher will have at least four points in more than half the possible scenarios (53.70% of them). The safety that comes with being in the top half of this group is counterbalanced by the fact that being in the bottom half is death. Other groups’ members know that their worst team will not advance (and their second-worst might not), while Group A teams know their three worst teams will not advance (but their top three almost certainly will).

As it applies to Nashville SC in particular, getting to that four-point threshold is paramount. Nobody knows for sure how much quality each opponent brings, given the limited information we have. It won’t be an easy task against a Philadelphia Union team that finished third in the East last year, a Chicago Fire FC team that comfortably won a 3-1 preseason friendly against this very Nashville side… and also Orlando City SC.

UPDATED 6/22: Fourth-place totals for Group A below.

MLS is Back Group A
Fourth-place team points Number of outcomes Percentage
6 168 0.86%
5 243 1.23%
4 10,158 51.61%
3 7,051 35.821%
2 1,935 9.83%
1 126 0.64%
0 2 0.01%



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