To me Jorginho isn't he issue in the midfield, it's the Kovacic spot. He doesn't track back well and he isn't great moving forward.
Jorginho is the issue to some because it's forcing Kante to play in an unfamiliar position. If Kante wasn't on the roster , I don't think people would be so hard on Jorginho, but then again, it's England. I think people find it hard to separate the two.
Sarri wants that position to provide things Kante can't , and he's essentially trying to grow him into the Allan role. I rate Kante higher than Allan , but he doesn't have the technical quality the Brazilian possesses, imo. I still believe Kante can grow into that role , and make it his own, but people are so bloody impatient. No more so than Chelsea supporters, who are ruthless. Roman has built a culture of only caring about today , and the supporters have adopted that mindset.
As for Kovacic, he's essentially in the Hamsik position, when he should really be playing in the Allan role. Sarri wants that position to be dynamic, incisive and daring, but that's just not Kovacic's game. In theory, Barkley would fit that role much better, but he's just not a high enough quality player (imo).
On the left of defense you have Alonso and David Luiz who get exposed defensively and Alonso hasn't been good moving forward this season.
They're both pretty average defensively , without a doubt. I've never been an Alonso fan, he just has a total lack of appetite for working hard/defending , and despite being quality going forward (at times) , he's just not good enough in that regard to off-set his deficiencies defensively (like a Marcelo, for instance).
Luiz , as most know by now, is fine in a 3-man defence when he has protection and his lack of awareness/concentration/positioning can't be exploited to the same degree. I also think he's just not as good as he used to be. It happens to everyone.
That said, I think all the players on the roster can gradually find ways to become productive pieces of Sarri's system. They just need to get it drilled in their heads , and then each player can find their niche , and Sarri can tinker to fit each player's attributes.
But the basics have to become instinctual first. Time is the only solution. Right now, there's several players who simply just don't understand what they should be doing , or worse, they're refusing to follow instructions.