The European champions have used just 20 different outfield players during their 22 outings so far this season, and the interim boss has started outlining his January targets
The Champions League holders travel to Japan for their Club World Cup semi-final on December 13 - naming a strong squad including the likes of Juan Mata and Fernando Torres.
Chelsea have used just 20 different outfield players during their 22 outings so far this season - including the now departed Raul Meireles - and Benitez has confirmed that targets for the January transfer window have already been discussed.
"You analyse the players who have played every game; there aren't many players here," Benitez told reporters.
"They'd been playing fewer players. I'm not here to criticise, but that's the reality. They'd played so many games, two a week and massive games in the Champions League, the players were getting tired. You can't give them a rest, either, because there's no time.
"They were asking me my opinion on what we need [in the January transfer window], and I said it was too early. I was pleased they were asking, but I need a couple of games [to make a decision on signings].
"[Daniel] Sturridge is injured. [Victor] Moses is the only option we'd have, but he's a different kind of player. Six training sessions, two games [so far and] I can't adjust too many things.
"I'm trying to keep the same team more or less and adjust little things. If we have to manage players like Fernando, we'll do it. But it'll be the same as Mata and the others. If I have another player who can play in his position, I'll do it."
Chelsea host West Ham on Saturday, and Benitez revealed that he was watching then Newcastle striker Andy Carroll while in charge of Liverpool, with a view to a purchase.
The Magpies turned down the offer, with the striker, currently on loan at Upton Park, eventually moving to the Reds in a £35 million deal in January 2011.
Benitez added: "He played in the FA Youth Cup at Anfield and we were watching him, a young player with power. It was an option, he was cheaper. £35m? Take the 'three' off. Quite cheap."