If you had said to that Bavuma that, four months and one chastening series loss to Australia later, he himself would be orchestrating a feel-good series win against West Indies - both as Test captain and as Player of the Match in the series decider - he may have praised your imagination. But that is exactly the kind of magic turnaround cricket sometimes provides.
This time, Bavuma could look every fan in the eye in the Wanderers crowd - admittedly there weren't many of them, given that the Test started mid-week and ended midway through Saturday - and with a smile after his series-defining century in his first rubber as captain. It turned out that four months is a long time in cricket, long enough for a complete turnaround for a player and a team that had been spiralling.
"What happened in Australia took place a long time ago," Bavuma said after his side's 284-run victory. "What happened in the T20 World Cup, it's in the past now. It's happened and I've moved on from it. I'm here now and my mind is in a different space now."
Bavuma had to return to Australia after that defeat, for a Test series in which South Africa had been lucky to lose just 2-0, and in which they had extended their stretch of sub-200 to seven successive innings. He was at least South Africa's leading run-scorer in that series, with 185 runs at 37.00 with a solitary fifty, but finished below three Australian batters.
The series was chastening for a team that had previously won three successive series in Australia but Bavuma took it as a teachable moment and wanted to come back better. "It was tough in Australia and as players, we were all under pressure," he said. "There were things that I learned in Australia and when I returned from the tour, I sat down and thought through them. I looked at where I needed to improve my game and I hope the results were there for everyone to see."
A key criticism of Bavuma over time had been his strike rate. In T20Is, it is considered too low for him to even make the team, and he has since been dropped after standing down as captain; and in Tests it was also sluggish enough for it to be cited as one of the reasons he had only scored one century in 54 appearances prior to this series. Despite that, South Africa's new Test coach, Shukri Conrad, saw something in Bavuma that he liked and decided he was the man to captain the Test side - a factor in his relinquishing of the T20I reins to concentrate on the formats he is strongest at.
"It's no secret where the side has come from. Australia was really dark," Conrad said. "We spoke honestly and candidly about Dean [Elgar] no longer being the captain. That's the only way one moves on. Dean also appreciated that. For Temba to step up the way he has ... we've also got key guys in that changeroom who perform leadership roles without being at the forefront of team conversations. The fundamentals and the cornerstones are there for this team to grow from a culture point of view."
In the end, Bavuma's 172 was the difference in the second Test and signalled a second coming for a batter and a leader who has always been under pressure because he is the first of his kind. Bavuma is South Africa's first black African batter and captain and he has now established himself as the person to take the Test game forward.
"As a leader you want to lead from the front," he said. "Me being a batter, it's at the top of my mind that I want to score runs. And I want to be able to speak with good authority in the dressing-room. This Test, things went my way. It's unfortunate that we are only playing our next game in December. We need to make sure we keep ourselves in check and make sure our cricket is going in the direction we want it to go."
Firdose Moonda is ESPNcricinfo's correspondent for South Africa and women's cricket