As some others have highlighted about the show, the writers have kind of lost that flare and the punch need to make the audience grip the hand rest of their seats.
In my opinion things started falling apart when Thomas Gibson was fired.
Well to the producers the Code of Conduct of the actors matter but still firing your lead role who was the perfect person for that role does a lot to the show.
However, along the way they did find some spark and had few very brilliantly executed episodes but it all died away.
The strategy of the team became more and more clouded so as the judgement of the crew working behind the series.
They need to find a way to bring that spark back and write some amazing episodes which if not possible means the series has reached its saturation point and need to find a way to end it.