How to split teams so the match is actually close
Why picking captains produces one sided games, and four methods that do better, including the one this app uses.
The best amateur game is the one that ends 6 to 5. The worst is the one that was over by minute fifteen, and everybody knew it during the warm up.
Teams get picked badly for a reason that has nothing to do with anybody being unfair. Two captains alternating picks is an algorithm, and it happens to be one with a known failure mode. This is what goes wrong, and four things that go wrong less.
Why two captains picking alternately produces a blowout
Captains pick in the order 1, 2, 1, 2. That looks symmetric and is not, because the gap between the best player and the second best is usually larger than the gap between any other adjacent pair.
Team A takes the best player. Team B takes the second best, who is meaningfully worse. From there the picks are close to equal, so the original gap never closes. The first pick is worth more than every later pick put together.
There is a second problem, and it is the one people actually notice. Being picked last, in front of everybody, every week, is a small humiliation delivered publicly, and it is a common reason somebody quietly stops coming.
Team A picks 10, 8, 6, 4, 2 total 30 Team B picks 9, 7, 5, 3, 1 total 25 Team A is 20% stronger before anybody kicks a ball.
Method one: the snake draft
Sort everybody by strength and pick in the order A, B, B, A, A, B, B, A. The team that picks first in one round picks last in the next, so the first pick advantage is paid back immediately.
On the same ten players a straight draft gives 30 against 25. A snake gives 28 against 27. It costs nothing, it takes the same amount of time, and it is the single largest improvement available to a group that picks by hand.
It still needs somebody to rank the players, which is the part groups avoid, because saying out loud who is seventh best is unpleasant.
Team A picks 10, 7, 6, 3, 2 total 28 Team B picks 9, 8, 5, 4, 1 total 27 A one point gap instead of five, from the pick order alone.
Method two: let the results do the ranking
Nobody has to rank anybody if the table already did it. After a dozen matches, points per game is a defensible ordering, and it has the advantage of being a number rather than an opinion somebody has to defend in the car park.
It is not perfect. A player who has been on strong teams accumulates points that are partly not theirs. But it is unbiased in the way that matters: it does not know who is friends with the captain.
This is the point where recording every result stops being bookkeeping and starts paying for itself.
Method three: account for who plays well together
Two players of equal individual strength are not interchangeable. Some pairs work and some do not, and a group that has played together for two seasons knows which is which without being able to explain it.
The record does explain it. If two players have been on the same side twelve times and won nine, that pair is worth more than the sum of the two players, and splitting them makes both teams weaker in a way a skill ranking cannot see.
The same is true against opponents. Some players consistently do well against one particular other player, and putting the two of them on the same side wastes it.
Method four: what this app does
Sunday Super League builds a split from four weighted factors. The weights are visible rather than hidden, because a suggestion nobody can interrogate is a suggestion nobody trusts.
How the candidate splits are generated
One method would find one answer. The app runs four and keeps whichever produces the smallest predicted gap.
A snake draft on the skill rating. A synergy pass that starts the two strongest players on opposite sides and assigns everybody else by who they play well with. Ten random splits, each improved by swapping pairs between the teams for as long as swapping helps. And for ten players or fewer, every possible split, which is 252 combinations at ten and finishes in under a fifth of a second.
Above ten players the full search stops being possible, 20 players is 184,756 splits, so it keeps the best hundred candidates from the other three methods instead.
The output is a suggestion with a balance score, not an instruction. The admin can regenerate it or ignore it. A machine that insists is worse than a captain who listens.
The uneven teams problem
Nine people turn up. Somebody plays 5v4, and the team of four is not four fifths as strong, it is worse than that, because they cover more ground each and tire sooner.
The app adds 8% to the shorter team's strength for every player they are missing, so in a 5v4 the four get an 8 point bonus before the two sides are compared. That pushes a stronger player onto the short side, which is what a good captain does by instinct.
If you are splitting by hand, the rule of thumb is the same: the short side gets the best available player, not an equal share of them.
What none of this fixes
Balance is a prediction, and predictions are wrong. A perfectly balanced split still ends 7 to 1 sometimes, because somebody had a bad night or a keeper had a great one.
Judge the method over a season, not over a match. If most games finish within two goals, the split is working. If one side wins by five most weeks, the ranking underneath it is wrong, whatever produced it.
Switch from a straight draft to a snake draft and most of the imbalance disappears. Everything after that is refinement.
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