|Paços de Ferreira defend poorly and FC Porto end up scoring.|
Notice the huge amount of space behind both Paços players (yellow area)
In this particular play, Hulk goes up against two Paços players. The first one (red circle) is doing the right thing by protecting the middle (and simultaneously Hulk's strongest foot). However, the second defender should be providing coverage for the first one, with the arrow indicating where he should be, ideally. Because he wasn't, Hulk was able to speed up, get past both opponents and cross for another defender's interception into his own net.