In my opinion, there are two issues that are causing Gyokeres to look the way he is looking right now, which is pretty ineffective and pressing to make an impact.
The first is that, as est said so well, we are not manufacturing chances for him to convert. I was not expecting him to come in this year and have similar numbers in terms of goal output as he has in the last few seasons. However, I was expecting him to get on the end of threatening balls into the box and finishing those - something that Kai is not always the most adept at due to positioning and ball striking. But I am struggling to count on one hand the amount of cutbacks we have aimed at him thus far in the season. We also have failed to manufacture many transition opportunities for him to capitalize on, outside of the tap in he had from Eze. Part of this has to be due to the amount of absences we have had thus far and the stop-start nature of our training as a result so I am hopeful if we can get a good run of health soon, we can work on incorporating more of this into our tactics and look to get him on the end of 1-2 of these chances a game.
My second concern is related to his physique - he really does seem to still be carrying an extra 10 pounds of weight and I feel like it has affected his pace and explosiveness. He is never going to be a nimble 9 who is able to change direction quickly and weave in and out of defenders but he definitely seems to be missing a gear in accelerating into space and just looks a bit heavy. I wonder if he tried to bulk up a bit to deal with the EPL physicality but it seems like that hasn't been a good decision since he also tends to end up on the ground a bunch when in physical duels. Hopefully with a run of good health, he can work back into shape and show the explosiveness he showed at Sporting. I also think that Kai coming back and allowing us to not play him every single match will help.