All goals conceded are down to individual errors. Especially for us when we concede from corners and set pieces. The tactical set up plays it part because we played a system that makes it difficult to break teams down that sit deep. You can't play it through the middle with Giroud. The longer we go without scoring a goal, the more vulnerable we are to being sucker punched because tiredness and lapses in concentration.
Pulis will always set up a stubborn team but our best result against his side came at the end of the 2014/15 season where Theo scored a hat trick. They sat deep and in numbers but worm to bits and we won 4-1. City beating them 4-0 recently is another example of what happens with a quick nimble striker can do to them. It makes no sense playing that way with Giroud against teams that park the bus.
Need to rewatch that Liverpool game but they scored two goals in the first half and conceded late on towards the end of the game. That suggests a different sort of game compared to ours.