PPDA (Passes per defensive action)
A metric to quantify high press intensity introduced by Colin Trainor in 2014*.
Only events in a subset of the field (final 60%), as described on the figure, are taken in consideration:
In this zone, we calculate all opponent passes that started there and divide them by the sum of defensive actions (fouls, interceptions, won defensive duels, sliding tackles) of the pressing team and divide opponent passes by defensive actions.
In the Liverpool-Manchester United match of 20 October 2019, Manchester United had 207 passes in their lower 60% zone, while Liverpool had 10 won defensive duels, 16 interceptions, 11 fouls and 3 sliding tackles in this area. 207 / (10 + 16 + 11 + 3) = 5.2. This is the value of PPDA for Liverpool.
In the same match, Liverpool had 404 passes in the lower 60% zone, while Manchester United had won 6 defensive duels, 10 interceptions, 4 fouls and 3 sliding tackles. 404 / (6 + 10 + 4 + 3) = 17.6. This is the value of PPDA for Manchester United.
Notice that Manchester United had allowed much more Liverpool passes in their defensive zone. Basically PPDA reflects how many passes in the opponent defensive zone the opponent can make per one challenge. The lower this number, the better the team is doing high pressing. In top five European leagues for 2018/2019 the average PPDA per season is 11.01. The best team in PPDA in top five leagues 2018/2019 is Eibar with whopping 6.72, and Nürnberg has the least PPDA (18.21).