Speaking on Sports Tak, Harbhajan stated that the Test series defeat could have had a "huge impact" on India.
"About Virat Kohli quitting Test captaincy... I think the result had a huge impact. Many people think about what happened. If Virat Kohli is insecure with this, then other players also are. What are the reasons behind him quitting captaincy, only he will know. But I feel quitting captaincy during the tour gave a small setback to the team for sure", he said.
Harbhajan also went on to state that this was India's perfect chance to defeat South Africa in their own backyard as they didn't have a strong team.
"It wasn't expected what happened in South Africa. Team India went there and I thought it was a good opportunity to defeat South Africa in their own backyard because they are known to have a very strong team; it used to be. But this Indian team lost to a team which wasn't that strong. I don't think they have many famous players and if you see their bowlers, they are not that great", he said.
"After losing the series, even Team India must be thinking that they lost a good opportunity as it was their biggest chance."
"If you see the SA team, they don't have AB de Villiers, neither Faf du Plessis nor Dale Steyn and Jacques Kallis."
"So it was a big chance missed by Team India", he also added.
Kohli had also stepped down from Team India's T20I captaincy after the T20 World Cup last year. Soon, he was also removed from ODI captaincy with Rohit Sharma announced as full-time white-ball skipper in December.