To be fair, City have had more players at the world cup and for longer, as did Chelsea.
I think it's more that some our absolute key players, in an attacking sense, played at the World Cup and haven't come back in sparkling form. Whether the World Cup is the reason or a coincidence I'm not sure we know without any sports science input.
I think Mane, Salah and Firmino are all struggling a bit this season. Salah probably had the most turbulent summer but he's probably been the best out of those 3 so far. Mane has been patchy but very good on occasions. Not sure how much the World Cup has affected him. Wonder how injuries have affected him recently. Firmino has been pretty average for most of the season. He didn't really play in the World Cup much but he has had a heavy workload over the last 18 months. Maybe he just needed that extended summer break that participating in the World Cup didn't afford him.
Our entire set up has generally been geared to get the best out of the front 3. It's slightly less so this year but it's still weighted towards them. It's why we play a 3 man midfield and ask them to cover the space of 4 men. It's why, on many occasions, we need physically and tactically strong midfielders over playmakers in that that midfield 3. It's all geared towards having 3 lads who can play upfront with very little defensive responsibility, in the main, once the ball goes into our half. That adds some pressure to the front 3 since most of the rest of the team is there to service them. They need to provide the vast majority of our attacking thrust and goal threat.
I'm not slagging the front 3 off. But we need to recognise that the system is geared towards them. Sometimes at the detriment of other parts of the team. If they don't then sparkle, then we don't have that much attacking threat. We really miss that 3rd midfielder who can join the attack and be the 4th attacker. To be a goal threat but also create space for the front 3. Think in the current squad Keita and Shaqiri are the only real options for that position that are fit.
Our performances have been OK to good for the vast majority of this season. The results have been excellent bar the 2 away defeats in the CL. We know we can play much better in an attacking sense. It probably needs the front 3 to give more in an attacking sense. It probably needs one of Shaqiri and/or Keita to really step up and demand a place in that midfield. They just haven't done enough to suggest they are undroppable so far. Get those 2 things and we'll be flying. That's what we got about this time last year. The front 3 (plus Coutinho) started to hit form. As we got to January onwards, AOC really emerged as that midfielder who can break the lines but also provide some attacking drive from midfield. That's what we need to see again.