SEATTLE — First baseman Josh Naylor is finalizing a five-year contract with the Seattle Mariners, according to ESPN’s Jeff Passan.

The deal would be the first major free agent signing of the winter.

Naylor was traded to the Mariners last season from the Arizona Diamondbacks, right before the trade deadline cutoff.

After joining the Mariners, Naylor played a pivotal role in pushing the team to the postseason with 32 runs, 58 hits, and an on-base percentage of .341.