Like the Tatas, the Mistrys are part of Mumbai's tight-knit Parsi religious minority, and Cyrus Mistry's sister is married to Ratan Tata's half-brother. Chandrasekaran, by contrast, was born into a south Indian agricultural family, joining Tata in 1987.
To pick Mistry, who succeeded Tata in December 2012, a five-man selection team spent 15 months searching. Chandrasekaran, who also sits on the board of India's central bank, was chosen in less than three months.
"Chandrasekaran's foremost challenge will be to regain the trust and loss of reputation of the Tata group and addressing investor concerns," said Shriram Subramanian, founder of Ingovern, a proxy advisory firm.
"One has to see what his relationship will be with the Tata trust and Mistry's holding companies, and whether he will be a yes-man to Ratan Tata. But from the competency perspective he is fully capable."
An avid photographer turned marathon runner later in life, Chandrasekaran has run Tata Consultancy Services - India's most valuable company, accounting for the single largest share of Tata Sons profit - since 2009.
Before taking on TCS from his leaf-fringed, colonial office in south Mumbai, Chandra, now 53, was seen by rivals and insiders as a backroom operator. He was strong on technology, they said, but low on charisma compared with industry peers such as Infosys Ltd founders N.R. Narayana Murthy and Nandan Nilekani.
Then 46, he was one of the youngest CEOs of the Tata group.
Critics forecast his quiet presence would struggle to engage the top bosses of overseas clients to win deals and retain existing clients in the cutthroat Indian outsourcing industry.
Chandrasekaran surprised: a cautious and meticulous manager, he embraced the sales role. TCS's shares and revenue have risen almost fourfold since he took over, while headcount almost tripled.
"Chandrasekaran instilled aggression into TCS," said Vibhor Singhal, vice president at Mumbai-based broker PhillipCapital. "It was under him that TCS forayed into newer geographies like Japan, and took to new automation platforms, like Ignio."
But his new role will test more than his sales skills - it will also call for diplomacy as he rebuilds ties and relationships.
"He is a professional, and not related to the Tatas which makes him unbiased, and that will help him in gaining confidence of small and large shareholders," said Deven Choksey, managing director at K R Choksey Shares and Securities.
"I expect the market to take this news
positively and Tata company shares to gain."
Married, Chandrasekaran lives in central Mumbai with his wife and teenaged son