I said this already in a separate thread, but since we are talking about it, I will say it again. I have said for 3-4 years now that Kaebi is not a defender, yet multiple coaches seem to think he is, and we pay for it time and again. The first KSA goal was due to him being in the wrong position, not to mention that overall he doesn't have the physique and mentality of a defender. We need a solid right back to replace him. He is a good player and we can use him in a more attacking role as the right midfielder.
As for the two central defenders, Westi put it best. We have two solid guys who are strong and good in the air, but they are both slow and speedy forwards can run right through the middle of our defense. I don't know if we have any speedy defenders in the center (Nosrati and Rezaii are both slow too), but maybe Sheys can fill that role along side either Aghili or Hosseni (probably Aghili). I haven't seen Sheys play recently, but the few times I did see him play, he seemed to have decent speed making runs up the field. He is also pretty tough and decent in the air, but I agree he is a little nutty (ozgal) from his off the field antics, but if the coach can control him, he might be a good choice. Aside from that, I don't know if there are some other young players in the IPL that would be good in that role.
Last, I disagree that it was the midfield that was the problem. Nekounam frequently helps back and I saw Khalatbari coming back to defend. I just think our defense needs an overhaul, and that our strongest line is our midfield. Offense needs help too, since we don't really have a clinical finisher, but I think our best chance is with someone like Borhani. Hashemian is just too old and not in form, and Rezaii and khalatbari are more hustle and good at creating chance, not real finishers. Khalili showed some signs of it, but he has been injured and I don't know what form he is in now, so I think Borhani is our best choice right now.
So, all in all, the only change I would make, is to introduce a good right back - maybe Heydari, for what I have heard - replace one of the central defenders with a more speedy one, and introduce Borhani into the attack.