Think the World Cup showed the amount of leverage you can take from simple set piece work.
Apparently inswinging corners are more likely to generate a shot, while outswingers are more likely to retain possession. I believe short corners are generally better than both - when a shot is generated from a short corner routine, your chance of converting shoots up.
Interestingly we are the worst side at attacking and defending corners in the prem this year, and Gylfi has the worst corner record in the league in terms of deliveries resulting in goals - that’s over a season or two that.
How much is system and how much is adapting to that newer system and how much is individual issues - not having a 6 foot 4 striker like we usually have etc.
I think it’s actually smart and progressive to put some work in on set piece routines, especially since we don’t have prolific open play creators (except for Bernard maybe & the whip crosses tactic). A lot of our chances have come from dead balls, but we’ve not been great at converting - big Micheal Keane the reverse Funes Mori who gets his head on EVERYTHING in our half, but turns into a total 50 penga head in the opposition box, should have had a few I think. Same for Zouma. Mina probably will make a difference but probably not as much of a difference as better set piece routines.