Taking as a given that Martinez will be an outstanding hitter in the middle of the lineup, this signing - along with the signing of Eduardo Nunez earlier in the weekend - gives this Red Sox offense the most depth they have had since the 2013 champions. That team taught us that it makes good baseball sense to go a few players deep at each position if you can, and to not obsess with how you'll find at bats for everyone. Here we go again with that approach.
The 2018 Red Sox are remarkably deep and flexible. When someone gets hurt, the likelihood is that that player will be replaced in the lineup by a one-time All Star. Should Devers, Bogaerts or Pedroia get injured or when they need a day off, Nunez can play all those positions. Should Moreland, Martinez, Benintendi, JBJ or (probably) Betts go down, Hanley will essentially sub in for them, either directly (Mitch & JD) or indirectly with the outfielders where presumably Martinez would see some reps out there with the B's rearranging themselves to cover for their fellow fallen dancer. Add in the Blake Swihart who may go Steve Lyons on us this year - omni-positionally, not cognitively - , and this is a lot of flexibilty for a 3 person bench (not including backup backstop Sandy "Remember When I Hit" Leon). And on top of all that, Nunez can apparently play some outfield as well.