Disappearance of home advantage this season?

I have become quite fond of the “rates diamond” graph that I developed in order to compare teams’ home and away points rates. Below are the final diamonds for this season, for 6 leagues; and for the English Premier League I have also drawn the corresponding graph for the 2018–2019 season, for comparison (i.e., the last full “normal” season before the pandemic hit).

For the Premier League, the contrast between this season and 2018–19 is striking! And 2018–19 is fairly typical, I think, of how such a graph looks in a “normal” season. It appears that the familiar and more-or-less constant feature of substantial “home advantage” has disappeared in the current season. The absence of supporters on matchdays has presumably played a big part in this. No fewer than 11 of the 20 clubs in the Premier League amassed more points when playing away than at home, in the 2020–21 season.

For the other 5 leagues, the picture is mixed. France’s Ligue 1 shows a similar pattern to the Premier League, and indeed is in some ways more extreme (with 14 of 20 clubs doing better away than at home). The other leagues have most clubs still doing better at home than away; but perhaps even there, there are more clubs than normal that have gained more points on the road than when playing at home. (I have not checked previous seasons, for those other leagues.)