CC Sabathia landed what was then the richest contract for a pitcher in major league history when he signed a seven-year, $161 million deal with the Yankees before the 2009 season.

It won’t take that large of an investment to keep DJ LeMahieu in The Bronx, but Sabathia knows how unpredictable free agency can be.

“When I was a free agent, I didn’t know what it was like to step into the Yankee clubhouse,’’ Sabathia said Monday while promoting “Under the Grapefruit Tree,” his HBO documentary. “[LeMahieu] knows what it is to play in front of a packed crowd. He proved he can play in New York and everyone wants him to stay, but you don’t expect anything [in free agency], because you never know how it’s gonna turn out.”

With the news that the Yankees and LeMahieu are more than $25 million apart in negotiations of a four- or five-year contract, it’s clear that’s true even when both sides want a reunion.

Sabathia, a special advisor with the Yankees, said he talked to LeMahieu recently, but not about a potential deal.

“He’s a great teammate, a great player and fun to be around,’’ Sabathia said. “And he hits like the machine.”