Martinez will not exercise the opt-out in his contract, Jeff Passan of ESPN.com reports.
Martinez evidently didn't feel as though he could make more than the $62.5 million he's due over the next three seasons on the open market. He remains an excellent hitter, but there's understandably some uncertainty about the market for a 32-year-old designated hitter. He has opt-outs remaining after each of the next two seasons, so there's still no guarantee he remains in Boston through the end of the 2022 season.