Until someone actually becomes a president, despite years of experience, they remain untested.
Bush was a governor but was tested by 9/11, the war on terror and then by the disasterous war in iraq (despite surrounding himself with advisors who'd spent 40+ years in government like dick cheney)
Obama/Mccain were tested in 2008 during the financial crisis. Mccain, despite being in government for over 40 years failed that test.
Trump was tested by corona and we all saw what a mess that was.
Uhuru despite his wealth, urbane education, being the finance minister, being around power since childhood, has failed & you can argue that it's because he's a drunkard and chain smoker, but even if he had hired the right advisors, would he have made it? The presidency is unique.
The presidency is a hot seat and you never know how someone will perform until they sit on that hot seat. So, Ruto remains untested. The weight of an entire nation and the weight of 50 million kenyans will for the first time be on his back and we shall see how he performs or whether he out-performs the rest that have been total disappointments.
Africa is a grave yard of leaders that have failed their citizens. Not one has been able to move their country out of extreme poverty. RV Pundit and RV heavy hitter are trying to tell us that we are getting a genius, but Africans are used to disappointment, always and because of Africa's sad history, we remain skeptical.