Palmer has endured his most difficult season at Stamford Bridge, hampered by a persistent groin problem that has restricted his appearances and limited his influence. Rosenior is taking a deliberate approach to managing him through it.
"You give him confidence," the Chelsea head coach said. "You point out the things he's doing well. You point out the things that are still very, very positive in his game."
Rosenior has been going through the numbers to give Palmer a clearer picture of his actual impact.
"In terms of chance creation, I've gone through the stats. The chances he's created in our difficult times were very, very high for the league. We just didn't take the chances that he created. I showed him that."
He was clear on the kind of player Palmer is and what he needs.
"You can over-analyse at times, but that's not what I want Cole to do. Cole's an intuitive player. He needs to be free to express himself to the best of his ability."
Rosenior also explained the thinking behind managing Palmer's workload in recent weeks.
"How we have tried to manage Cole before this period is that there were question marks about why he was coming off, why he wasn't starting games. We wanted him fresh for this period, and so far, he looks really, really good for that."
The praise did not stop there. With Enzo Fernandez and Marc Cucurella both making headlines in recent weeks over potential moves to Spain, Rosenior pointedly drew a contrast with Palmer's attitude.
"I have to give Cole so much credit because he's put himself up to play for this club, maybe at times where other players wouldn't."
He was effusive on what Palmer represents to the squad and to his own plans.
"A lot of people speak about Cole's commitment to this club, how much he buys into what we're doing. He's fully invested in what we do, in many ways. I'm really, really delighted with him. Just him as a player, as a character, what he stands for, what he wants to achieve."
He closed with a clear statement of intent.
"He's going to be a huge part of things for me and the years to come."
Chelsea face City on Sunday needing a win to keep pace in the top-five race. They sit sixth, one point behind Liverpool with seven games remaining. Palmer starting against his former club — the one he left for £40 million in 2023 — could hardly be more fitting.