Mary Kay Cabot of the Plain Dealer spoke with Mack's agent Tim Younger and believes Mack would like to remain with the Browns.
According to Spotrac, he was slated to earn $24 million over the final three years of his deal.
On Feb. 22, Rapoport reported Mack was "expected" to opt out of his deal and chase a lucrative long-term commitment, so the news hardly comes as a shocker.
However, it could mean a serious shake-up for a Browns offensive line that looked like it had the pieces necessary to provide the team's offense with a solid foundation in the first year under head coach Hue Jackson.
ESPN Stats & Info provided insight into Mack's value for the Browns' running game:
ESPN Stats & Info @ESPNStatsInfo
Browns: 4.7 yards per rush on 157 rushes up the middle w/ Mack on the field 2014-15 (3.5 on 98 rushes w/ him off) https://t.co/oOUltP94zE2016-3-2 17:54:00
As CBS Sports' Joel Corry noted, Mack could angle for a deal that makes him the first center in the NFL with an annual salary of at least $10 million. Considering Mike Pouncey of the Miami Dolphins is currently on a deal that pays out $8.9 million, per Spotrac, a three-time Pro Bowler like Mack shouldn't have much issue fielding a hefty new contract with the salary cap rising.
And now that he's free from a Browns team that hasn't posted a winning record since 2007, Mack can pursue his dream of playing for a contender.
"I will say that winning is really important to me," Mack said, per Cabot.
Mack's value also figures to be bolstered by the fact that he displayed tremendous resiliency a season removed from suffering a broken leg.
"It's impressive that a guy that comes off of such a bad broken leg, and other injuries, is able to come back and he's to the point now where you don't even think about it," Browns left tackle Joe Thomas said, per Cabot. "You wouldn't even know, except for the scar on his leg, that he had a bad injury last year."
With the injury behind him and a proven track record of success, Mack should have no problem cashing out when free agency opens on March 9.