I agree that Martinez would be someone they should go hard after. But it DOES mean a glut in the OF, unless they either move Martinez to 1b or DH, the latter of which would force Hanley to 1b or get traded for a bucket of balls.
If neither of those is going to happen, it means the Sox would then have to make a trade, and JBJ is the most likely candidate. Then trade JBJ for a 1b with some power. Or go the platoon route and trade JBJ for prospects and sign Matt Adams to platoon with Travis.
Adams vs RHP (career): .286/.333/.495/.828
Travis vs LHP: .381/.458/.500/.958 (SSS)
That could be a fairly potent 1b combination if you platoon them, though the defense would be shaky.
Lineup:
SS Bogaerts
CF Benintendi
RF Betts
LF Martinez
1b Adams/Travis
DH Hanley
3b Devers
C Vazquez
2b Pedroia when he returns; until then, whomever
That's not as good as the Yankee lineup, but that's a lot more power for not a crazy amount more cost compared to 2017. Your defense is weakened some, but you also add the prospect(s) you get for JBJ.