The Spain international, who is widely regarded as failing to live up to his £50m price tag, was the Blues' first-choice striker until Ba's £7.5m switch from Newcastle last week.
While Torres remained on the bench for Saturday's 5-1 third round FA Cup win over Southampton, the newly-signed 27-year-old made an immediate impact, scoring twice on his debut.
"Ba coming will be better for Torres, 100 per cent," interim Chelsea manager Benitez said. "Not many players play every game in a top side, as he has had to, and now it will be positive for both of them.
"They will be fitter, maybe they will score more goals because they will have more chances and will be in better positions.
"Fernando is an experienced player and he knows football. We have spoken to both of them and they each know the role of the other, that they'll have a lot of games and will have a big part to play.
"Every session I can see Fernando is training well and trying to improve. Even when he's not scoring, he's working hard and doing things for the team.
"We have tried to fix things to improve his strength, a specific programme. If you do that, normally he can be quicker. It takes time, and I think it's improving.
"He's a bit quicker, but the biggest problem was he was playing too many games. Especially against QPR, some players were a bit tired, had too much fatigue. But having both Torres and Ba means both can do well."
Torres could return to the Chelsea line up for the Capital One Cup semi-final against Swansea on Wednesday, with Petr Cech, John Terry, John Obi Mikel and Victor Moses all remaining on the sidelines.
The Stamford Bridge tie kicks off a busy period for Benitez's men, with eight games in 25 days to contend with.
"When you are a top side you know you have to play twice a week, but because of Japan and the time we had to go there, we have been playing a lot of games," Benitez said.
"It's difficult for us to plan and prepare training sessions. Monday's was another light session and you can't do everything you want to do.
"We have to try to do tactical adjustments in every session, so it's quite complicated, but in a top side it has to be like this."
And Benitez has also warned fans of changes to the squad, refusing to rule out the possibility that popular players could leave the club.
"I think it's always easy to talk about the legends, and you have to have a lot of respect for them because what they've achieved for this club has been fantastic," Benitez added.
"But you have to have new players - it could be English or foreign, it doesn't matter - and carry on winning games.
"That's what the fans are expecting. Everyone knows the legends have been here and what they have achieved, but you have to see new players coming. It's part of life.
"You have good memories and you respect people who achieve something for a club. That's very positive.
"But, at the same time, you have to think about the future. You cannot be waiting.
"You have to move forward, bring in new players and at the same time try and bring the best out of those you have. You have to use their experience, too."