The Vodafone 4R Electrical Men in Black came alive in the second spell after a lacklustre and hasty performance in the first 45 minutes in which they received four yellow cards.
The big win puts the local champions in the driving seat in Group C with six points ahead of Tafea FC with three points and Hekari United and AS Magenta tied with a point each.
Ba coach Yogendra Dutt made four changes to the starting line-up which defeated AS Magenta 2-0 on Monday relegating Avinesh Suwamy, Marika Madigi, Mavileko Nakama and Josefata Neibuli to the bench.
The home side failed to settle in from the opening whistle with Peni Finau, Meli Codro, Jone Vesikula and Maciu Dunadamu copping yellow cards from referee Matt Conger.
Dalong Damalip should have put the visitors up in the 20th minute after a neat pass from Joses Nawo. However the 20-year-old blasted the ball over with only goalkeeper Epeli Codro to beat.
Moments later Vakatalesau hit the cross bar with his header following a corner kick.
An own goal gave Ba the best possible start in the second spell after pressure from Dunadamu. Vakatalesau then set up Dunadamu to score the second goal in the 51st minute.
Tafea FC was reduced to ten players after Kevin Sham received his second yellow card in the 82nd minute. From the ensuring free kick replacement Shameel Rao tapped the ball in from close range.
Nakama scored the fourth goal in the 90th minute as the visitors seemed to tire out in the wet conditions.
Ba coach Dutt said their change in tactics proved fruitful.
He applauded the efforts of the substitutes to score late in the fixture.
"In the second half things started coming up well for us," Dutt said.
"We must remember that Maciu is playing top level football after a lapse of eight months.
"He started getting into the tune of things in the second half and then the front line started working.
"Meli made havoc on the left side he was playing. It was tactical and mind games by the officials. The substitutes should be impact players and they did well."
Tafea FC coach Moise Poida said lack of concentration cost them dearly after halftime.
Poida said they failed to stick to their game-plan.
"We did very well in the first half and outplayed Ba," he said.
"At halftime we tried to change some things. Then the boys failed to stick to the game-plan. Ba punched the ball in front and scored.
"We conceded four goals. The ground was wet and the boys are not used playing on it. There was lack of concentration."
"We now have to win the next game to try to stay in the run for the semi-final."
In the final pool matches Ba will play Hekari United while Tafea FC will face AS Magenta.
Ba: Epeli Codro, Meli Codro, Ronil Kumar, Jone Vesikula, Maciu Dunadamu, Abbu Zahid Shaheed, Remueru Tekiate, Peni Finau, Osea Vakatalesau, Ronald Lawrence, Laisenia Raura.
Tafea FC: Seloni Iaruel, Lucien Hinge, Kevin Shem, Jais Malsarani, Jonah Turu, Bong Kalo, Edisson Stephens, Dalong Damalip, Joseph Namariau, Joses Nawa, Winjo William.