Table 1 A summary of our results, in question-and-answer format

Does scoring in games of different team sports follow common patterns?

Yes. The pattern of when points are scored and who gets them are remarkably similar across sports.

What is the common pattern?

Events occur randomly (a Poisson process). Which team wins the points is coin flip (a Bernoulli process) that depends on the relative skill difference of the teams on the field.

What might cause this pattern?

A strong focus on short-term maximization of scoring opportunities, while blocking the other team from the same. There is no evidence of strategic planning across plays, as in games like chess or Go. Teams largely react to events as they occur.

What determines how often scoring occurs?

Each sport has a characteristic rate (see Table 3), which increases dramatically at the end of scoring periods.

What determines who wins an event?

Skill and luck, in that order.

Do events early in a game influence events later in a game?

No. Each scoring event or ‘play’ is effectively independent, once we control for relative team skill (and lead size in basketball). Gameplay is effectively ‘memoryless.’

Can a team be ‘hot,’ where they score in streaks?

No. Just like players [19], teams do not get ‘hot.’ Scoring streaks are caused by getting lucky.

When is it easier or harder to score?

Every moment is equally easy or difficult. But, teams try harder at the end of a period.

Which sport is the most unpredictable?

Pro basketball, where lead sizes (spreads) tend to shrink back to zero. This tendency generates many ‘ties’ as a game unfolds.

Do other sports exhibit this pattern?

No. Pro basketball is the only sport where the spread tends to shrink. In football and hockey, the spread tends to grow over time.

Does being behind help you win, as argued by [21]?

No. Being behind helps you lose. Being ahead and being lucky helps you win.