FT Baseline Raheem Sterling: the stats behind the star

By John Burn-Murdoch and Gavin Jackson

In the first instalment of our new sport statistics series, FT Baseline, we have taken a look at the emergence and development of Liverpool and England attacker Raheem Sterling. Below, as will be the case with all posts in this series, is an outline of our methodology.

Having obtained performance data from Opta, we decided to split the list of matches involving Sterling into three groups. We wanted playing time and variety of opponents faced to be sufficiently large in each group to ensure the results of any subsequent analysis would be reliable.

Sterling missed a large part of the second half of the 2012/13 season, so we decided to use that entire season as our first group. In 2013/14, however, he was heavily involved throughout, allowing us to treat the first and second halves of the campaign as two distinct periods in his development as a player.

In order to show how his positioning, shot locations and overall output (as measured by performance data) are interlinked, we decided to split the analysis and visualisation of each time period into three parts.

Pitch heatmaps

For positioning and shot locations we grouped the on-pitch locations of every action into bins along the horizontal (Liverpool playing from left to right) and vertical (pitch width) axes, removing a lot of ‘noise’ from the data. For the activity heatmap, we used any event recorded by Opta where Sterling ws involved, including but not limited to passes (both attempted and received), shots, tackles, dribbles.

The area of a circle on both the activity and shot heat maps corresponds to the proportion of all of Sterling’s actions/shots in that series of matches. For the activity heatmap all circles have the same shading. For shooting, darker shades indicate higher accuracy.

Radar plots

The radar plots contain data adjusted by time played, such that each nominal statistic is given in units per 90 minutes, and the two proportional statistics are given across all matches played.

The bottom end of each axis (centre of the chart) corresponds to the fifth percentile of all attackers in Europe’s top leagues, and the top end (outer edge) is the 95th percentile. We stole the axis range idea from were inspired by Ted Knutson of football analytics site Statsbomb.

Performance data glossary

  • Goals: total number of goals excluding penalties
  • Shots: total number of shots, including inaccurate or blocked efforts
  • Goals/shots: goals as a share of all shots
  • Shooting %: share of all shots that were on target
  • Assists: passes that led immediately to a goal
  • Key passes: passes that led to a goalscoring opportunity
  • Passing %: share of all attempted passes that were completed
  • Dribbles: successfully took on an opponent
  • Dispossessed: lost the ball
  • Balls won: tackles and interceptions added together

Sources and acknowledgements

Throughout this series we’re keen for readers to join the debate, so if you want to ask further questions, offer ideas for who or what we should look at next, or point out flaws in our logic, please leave a comment below or email us on baseline@FT.com