To me it appeared that the MSM transitioned from very liberal to active functionaries of the regime when Obama appeared on the scene.
Their primary source of news comes from emails (by private email accounts, of course) from the WHITE HOUSE.
I put it at the end of the 2nd year of Clinton's first term. They had worked themselves into a pack frenzy during those first two years where Clinton's team was showing what sophomoric, puerile incompetents they were. The press suddenly caught themselves, realizing that they were doing actual damage to the face of the Gramscian project. They have exercised marvelous party discipline ever since.