I believe I am definig chemistry differently than you do. I see a connection between all the characters. Caring between all of them. They fit nicely together, especially the old team. If they didn't have that chemistry between all of them, I wouldn't like the show as much.

I don't see chemistry between Sam and Jack in a sexual way or a romantic way. I just see it in other ways -- mentorship, teammates, etc. I think the cast together always had great chemistry.

But if you think that it's not there, that's your perogative. I just don't think the show would have ever worked if they had zero chemistry.