Benitez credits the improvement of Fernando Torres, who has now scored 19 goals this season, including 12 in 25 starts under Benitez, to the specific fitness regime and gym work prescribed by fitness coach Paco de Miguel, who previously worked with Torres at Atletico Madrid and at Liverpool.
Benitez said: "From the first day Fernando was following a specific programme with Paco de Miguel and doing finishing work with Bolo Zenden [assistant manager] and Steve Holland [first-team coach].
"It was clear he needed to improve his fitness, his physical condition. And now he has more power in his legs. You can see that he can make a difference.
"It was improving his strength and speed. If you improve the strength, then a player of his quality will come through."
Benitez said Torres's loss of confidence was linked to the lack of power he had.
"It is a positive circle,' he said. 'If physically he feels better he will try to do more things and if he tries to do more things he will be more successful. If he doesn't try he will not change things. So it is positive.
"If he carries on scoring he could have some numbers that are not bad. The first week with Fernando it was a case of seeing where we were, then after he started improving, he was happy and he was scoring more goals and playing with more confidence.
"His problem was he was playing too many games in December, so by January he needed to rest a little bit. I said from the start that signing Demba Ba could be positive for him, so he could be fresh and a much better player when he played.
"Another manager with the same situation I think would have done the same. But the difference is when you have a Spanish player, who you brought from Spain, who was very successful with you, then you have a link, then you know what he likes to do and he can tell you things he might not be able to say to another manager."