On April 9, 2014, it was announced that the Jacksonville Jaguars had offered Mack a five-year contract, worth reportedly $42 million. The Browns had a maximum of five days to match Jacksonville's offer, which they did on April 11. Mack had been previously assigned the transition tag, nullifying his free agency unless a team signed Mack to an offer sheet. During Week 6 against the Pittsburgh Steelers on October 12, 2014, Mack was carted off the field due to a leg injury. X-rays tested positive that his leg had a broken fibula, forcing Mack out for the rest of the 2014 campaign. Prior to Mack's injury, he had never missed a single snap in his professional career. On March 2, 2016, Mack voided his contract with the Cleveland Browns thus making him a free agent.