One big difference in the players is that Kershaw has been an iron man, while Ramirez played only 86 games last year due to injuries to his thumb, hamstring, back and ribs.
As a former player, Mattingly said he knows how an uncertain contract status can be a distraction, and he raised the issue with Ramirez to make sure they were on the same page.
"It's a conversation I wanted to have. I didn't want it hanging out there," said Mattingly. "I've been a player, I know. He knows what I think about him as a player."
Ramirez said last week that he wants to be a Dodger "for life," but he was reluctant to discuss his contract beyond that.
An extension would probably come with the agreement that Ramirez move permanently to third base when the Dodgers have a shortstop replacement ready.
Mattingly said if Ramirez takes care of business on the field, the contract will take care of itself.
"When you worry about it, it takes away from the game," Mattingly said. "I do see this as a carrot. He knows at the end of the year if nothing happens, there are 30 teams. Nothing wrong with that. It's what free agency is all about.
"He's in a great spot. Just go play. He's confident in what he can do. If we can keep him on the field, he'll be fine. I want Hanley to be a leader, and we saw after he won the [World Baseball Classic] last year, he was talking about winning, not about his at-bats. We've seen real growth in Hanley. He's been great."
Ken Gurnick is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.