The show was built to be anchored around 2 characters (Carrie & Saul)... That's what made it soar in the beginning, but its also the show's biggest anchor and impediment.
Additional characters organically develop in this series like Brody & Quinn, and others that become powerful enough characters that draw viewers just as deep if not deeper than the planned formula of Saul/Carrie. This not only spices the show up but it relieves viewer fatigue of watching Carrier repeatedly go through her issues over and over in order to achieve interested dramatic effect.
These two major characters became critical and grew to carry this series to very new heights. Then the writers/produces irresponsibly ignore what these two characters brought to the show and it just seems writing/direction is forcefully introduced to steer the focus back to Carrie/Saul. And its very intrusive to the cohesiveness of the story and definitely leaves the audience feeling the show is become more artificial.
The other issue is that by removing both these characters the show is now VOID of any really "Good guys" leading characters... As time goes viewers learn both Brady & Quinn are the shows only seriously "good guys" on the show... They care and have a code of ethics way higher than Carrie or Saul. They are not perfect but have overwhelmingly redeeming qualities that make up for the bad. However, events really bring you to despise both Carrie and Saul for who they are. Viewers learn there is no loyalty and they both are ready to risk/do via force or manipulation to other good people under an illusion the risk is worth the reward...
They still personally believe they are good and do good overall but at their core nothing is sacred to accomplish what they need at all costs... and in the end both characters become sellouts to their own needs or masking it under many times very thin veil of country needs when it really was only for their personal interests.
I think the writers had a good formula here but they are now seemingly forced to keep the story rooted in Carrie and Saul and that has left the show void of a real hero people can identify with as they could with Brody / Quinn...
And the ridiculous writing on the demise of Quinn from the poisoning forward is amateurish at best and just shows the show is misfiring and not quite aware of what they fan base enjoyed about the program. Acting is super solid across the board... the only issue is maintaining the stories organic continuity and balance set aside some obvious cheese with Quinns repeated demises, and how they amateurly let a double agent station chief in Berlin run amuck in active operations even after they know she's a snowden level traiter and weakly convinces Dar Adal of otherwise... Hit a real cheese point there.