Hypothetically, because we have not done it, but if we did deploy the diamond we would defend with three midfielders behind Wirtz, who would be behind Isak and Ekitike. Grav, Szobo and Macca/Jones would give us a good solid trio in the middle.
The fullbacks would provide overlapping width, using their stamina to get up and down the flanks. If possession turned over Grav at the base of the diamond would slot into a back three to give defensive solidity.
Based on the players we have now, I think it would be much better than what we have seen. If Slot intends to play with wingers (and he is still here) he needs to buy one or two, as neither Gakpo or Salah, for different reasons, are elite.
How would we press in a diamond? I can only talk in concepts, as it would need to be dialed in on the training ground and with reps on the pitch in a match situation. But no passengers, everyone working hard and putting in the running. Pressing in a trio, or a four, moving in concert, cutting off passing lanes, taking away options for the defending team to either win it back directly - Wirtz in the past has been very good at getting his toe in, or the press would force them to do a bad pass and we get the ball back that way.
Based on the players we have I would like to see a diamond tried. It has the potential to get our attacking talent on the pitch and even though the vast majority of teams stay away from this system, there’s no reason why we can’t innovate by cracking it, given the players we have.
Alternately, if we signed, say, Semenyo, I could see a 4231 coming to the fore with Ekitike-Wirtz-Semenyo behind Isak. Bold in an attacking sense for sure, and the others would need to be compact to ensure enough defensive stability.