The straight-talking Matiang'i was regarded as third-in-command, after Uhuru and his deputy, by virtue of him being the "prefect" of other cabinet secretaries. He chaired meetings of CSs to track progress of the programmes they were undertaking before reporting to the president.
The CS was given the supervisory role in 2017 after it emerged Uhuru and Ruto had fallen out.
Matiang'i went ahead to play a key role in Raila's campaigns, especially in Kisii County, even as he worked hard to push the government's agenda.
He campaigned for Raila in Kisii and Nyamira counties. Matiang'i attended some of Raila's rallies.
Other members of the Abagusii in Uhuru's government are Health PS Susan Mochache, Solicitor General Kennedy Ogeto, and county commissioners Rhoda Onyancha and Evans Achoki, Central Bank chairman Mohammed Nyaoga and Controller of Budget Margaret Nyakang'.
Others are Kisii University Vice-Chancellor Prof John Akama, Murang'a University of Technology Vice-Chancellor Prof Dickson Nyariki, Nacada CEO Victor Okioma and National Research Fund CEO Jemimah Onsare. Akama, Nyariki and Okioma are from Nyamira County while Onsara is from Kisii.
Zachary Ayieko, the Chief Administrative Secretary in the Ministry of Energy, is also from the region.
Recently, South Mugirango MP Sylvanus Osoro, said: "We had people from this region holding key positions in the government yet we are still struggling. Some of the promises made to our people were never fulfilled. Individuals from our region appointed to government should be those with the best interest of our people at heart."
Osoro, a key ally of Ruto who has been proposed for the position of of Majority Chief Whip in the National Assembly, accused some of those appointed by Uhuru of joining government to self-seek.
As soon after the Supreme Court upheld Ruto's victory, some Gusii leaders allied to Azimio La Umoja met the President Ruto and promised to work with his government. They included Kisii former governor James Ongwae and former Woman Rep Janet Ongera, who led a host of leaders from Kisii and Nyamira counties for a meeting with Ruto in Karen. The meeting lasted about three hours.
Ongwae was Raila's pointman in the Gusii region while Ongera served as ODM's executive director and was a key ally of Raila.
Former Transport Chief Administrative Secretary Chris Obure, who unsuccessfully ran for Kisii governorship on the Jubilee ticket, and Abagusii Council of Elders chairman John Matundura, among others, also attended the meeting.