The Austrian duo were installed in management positions with the team in 2013, but Brawn, who sold the team to the German marque in 2009, felt that he could trust the pair.
"What happened at Mercedes is that people were imposed on me who I couldn't trust," he admits in his new book Total competition which he co-authored with former Williams executive Adam Parr. "I never really knew what they were trying to do. I mean Niki would tell me one thing, then I would hear he was saying something else."
"I was beginning to deal with people who I didn't feel I could ultimately trust," he continues, "people within the team, who had let me down already in terms of their approach.
"Then in early 2013, I discovered Paddy Lowe had been contracted to join the team and it had been signed off in Stuttgart. When I challenged Toto and Niki, they blamed each other. I met them to have it out with them. And they both pointed to each other," he said. "I couldn't trust this people, so I saw no future unless I was willing to go to war and remove them. I saw no future with people that I didn't feel I could trust."
Bahrain International Circuit - Winter testing