agreed to terms on a deal
According to FanRag Sports and MLB Network's Jon Heyman

After posting a mediocre slash line of .251/.300/.387 with just 24 homers and 126 RBI in his first three years with the Houston Astros, Martinez has transformed into a .300 hitter with immense power over the past four seasons.

With a slugging percentage near .600 over that span, Martinez has hit 128 homers and driven in 350 runs.

The veteran now provides a huge power boost that Boston's lineup had been missing, since the retirement of designated hitter David Ortiz two seasons ago.

Last year, the Red Sox finished last in the American League in homer runs hit, a stat likely to change with Martinez in the mix.