Papelbon is entering the final season of a four-year, $50 million contract, the largest ever given to a relief pitcher. Robertson's former team, the Yankees, aren't likely to match such an offer if the 29-year-old right-hander receives one, per Marchand.
Robertson posted a 3.08 ERA with 39 saves for the Yankees in 2014. He struck out 96 batters and walked 23 in 64⅓ innings, a performance that impressed New York general manager Brian Cashman.
"He is helluva pitcher that did it in the toughest environment after the greatest player of all-time and he did it with ease," Cashman told Marchand, referring to Robertson's unique circumstance of having to fill Mariano Rivera's shoes as the Yankees' closer. "I would suspect that would command top dollar."
Robertson declined a $15.3 million qualifying offer -- one that would have made him the highest-paid reliever in a single season in baseball history -- from the Yankees earlier this week.