JD Martinez
After being released by the Houston Astros in 2013, JD Martinez remade his swing and became one of the premier hitters in all of baseball. After stops in Detroit and Arizona, the Red Sox signed him to a five-year, $110 million contract in February 2018 to fill the void left by David Ortiz retiring after the 2016 season.
The 2017 Red Sox struggled to replace Ortiz’ production and had a down offensive year as a team. Martinez slid seamlessly into the cleanup spot in the order and helped power the Boston offense to their greatest season in franchise history. Martinez flirted with the Triple Crown all season and finished the year hitting .330 with 43 home runs, 130 RBI, 111 runs scored, a .402 OBP, and an OPS of 1.031.
That postseason he hit .357 in the ALDS, .278 in the ALCS, and .278 in the World Series with a combined three home runs and 14 RBI as the Red Sox won their fourth World Series of the century. He followed it up with a slightly down season in 2019, but only when compared to his own lofty standards; it was a season anyone else would have been thrilled with.
Martinez hit .304 with 36 home runs, 105 RBI, 98 runs scored, a .383 OBP, and an OPS of .939 in 2019. With the possibility of Martinez opting out after the season (he has an opt-out for each of the final three years on the deal), there was a real fear that the Red Sox would lose his bat, especially since he was on a relatively cheap deal.
Instead, he opted to stay and will be on the Red Sox for the 2020 season (whenever that may start). Martinez has carried the torch from Ortiz in providing monster production in the heart of the order and combined with the money the Red Sox are paying him, is one of their best free agent signings ever.