"We have recently seen brilliant moments from Mercedes, but they lack consistency," said the German at a sponsor event in Las Vegas.
"But if we look at Austin, for example: there, they fought for the win and had the fastest car over the weekend.
"So, we see that they are starting to understand the car. Because I've been there myself and know how strong they are. It's still the same people."
Rosberg remains neutral
Despite acknowledging the team's potential, Rosberg remains reserved in singling out specific drivers for his endorsement, adopting a neutral stance when it comes to Lewis Hamilton's potential eighth world title.
"I would be glad if Mercedes won because that's my racing family from the past," he said.
"As for Lewis, I am neutral."
In essence, Rosberg hopes for an exciting and competitive championship, emphasizing, "May the best driver win. As for that, I don't take sides."