How often does an XI appear on the field?

River Plate pre-kickoff photo, Argentine Superliga 2018/19.

One question that pops up from time to time in football punditry is the following: How often does a manager’s preferred eleven appear on the field? It may take a while for that preferred eleven to reveal itself, but the idea is that once it is known, it will appear as often as possible.

Of course, the exact XI doesn’t appear in every match because of injury, suspension, or manager’s decisions such as rotation or disciplinary action. But the original question remains a good one. And let’s extend the preferred eleven to any eleven, or even any combination of players. How often do they appear in the league season?

Determining the specific combinations isn’t very complicated as far as analytics tasks go, but it does involve some detailed bookkeeping, and implementing it in a computer program involves some clever use of data structures. But I carried this analysis out for some select teams in the 2018-19 Argentine Superliga — the league champions and runner-up, a representative ‘big’ club, and a representative ‘small’ club that fought off relegation.

Frequency of player combinations by select Argentine Superliga teams in 2018-19 season. Data supplied by DataFactory Latinoamericano.

Over a full league season (25 matches in the just completed Superliga season), about 90-95 different combinations of players appear on the field of play. Most of these combinations are spurious and appear for a few minutes. One or two combinations appear for around 200-400 minutes, which would be from 5-15% of total match time by a team in a season.

In this example, Defensa y Justicia’s most frequent lineup appears about 16% of the league season, or close to 400 minutes. That amount seems low at first glance, but actually makes sense when you consider injuries, suspensions, and the usual chop-and-change. Racing’s most frequent lineup appeared in 10% of their total minutes, or close to 240 minutes. I found it very interesting that Boca’s most frequent lineup appeared only 3% of the time, but that figure encompasses two managers, so it would be interesting to observe the differences between the lineups of Guillermo Barros Schelotto and Gustavo Alfaro. For a small club like Patronato, their most frequent lineup appeared in 5% of their total minutes, and the frequency of their other player combinations was not all that different from Boca’s.

There’s not really a deep analytical meaning here, although I would imagine that one could overlay some analytics on the distinct player combinations. I thought it would be interesting to understand which lineups a manager preferred to put on the field and how often those lineups appeared. So expect to see this in upcoming analyses of past and present competitions.