Khedira has experience in different teams at the highest level. Maybe he understood and managed to better translate what new changes in our gameplay Sarri asked for.
Also its easier to impress when there are zero expectations form you.
From Pjanic and Ramsey, you may have such expectations and even if they deliver as expected, no one is impressed. Ramsey atm cannot even offer his standard work rate.
Bentacour + Emre are not that experienced and maybe they need a little more time to adapt in this Sarriball.
And Matuidi is not a versatile player and sometimes even looks too sloppy.
Khedira is always considered finished and he prolly did quite well and this swift backpassing with forward runs and counter attacks with long vertical penetrating balls, we ve seen that in the German NT.
What Sarri might not know, is that in the long run, he cannot rely on Sami 's presence...