The 2015/16 season of the English Premier League is underway. The rolling analysis of that season is here. This post explains how to interpret the heatmap, using the results from the 2014/15 season.
The heatmap below shows how each team in the league fared against all others in terms of points scored. The row order matches that of the final points table at the end of the season. The initial column order is also by points. The colour of each cell indicates the points scored by one team against another.
For example, the eighth cell from the left on the first row shows Chelsea’s record against Swansea. The cell is blue, to indicate that Chelsea took all the available points off Swansea. That is, Chelsea won both of their games against Swansea that season. (Hover over the cells for more detail.)
Similarly, the left-most cell in the bottom row, in yellow, shows that QPR took no points off Chelsea. They lost both games.
Presented in this way, we can see how different teams fared against others by league-table position. Chelsea lost just once to a team in the top seven and won every game against the teams ranked 8-12 (the analysis by the BBC also shows this, in a different way). QPR didn’t beat a single team outside of the bottom eight.
By splitting out teams’ points in this way, we can also consider an alternative measure of team strength. The PageRank of a team takes account of the strength of the teams it beats. A strong team is one that takes points off other strong teams. The two buttons to the right of the heatmap reorder the columns by points and PageRank, respectively.
Reordered by PageRank, we can see how this alternative measure differs from that of the points table. Teams whose ‘own’ cell (in white) is to the left of the diagonal line are ranked higher by PageRank than by points. Conversely, teams whose own cell is to the right of the diagonal line are ranked lower by PageRank than by points.
By PageRank, the top two teams are unchanged, while Arsenal and Manchester United swap third and fourth place. Compared to their rankings by points, West Brom and Burnley gain the most places (three) by PageRank, owing to a few good results against the top teams. Everton and Leicester fall the most places (also three).
Data source: Football-Data