I know some of you are not big fans of WAR. I know their are issues and concerns. I have some of my own, but for argument's sake, let's use comparative positional WAR to see where are strengths and weaknesses are.
Position Season WAR ranking (2nd half ranking)
RF: 1st (2nd)
DH: 2nd (6th)
CF: 5th (14th)
1B: 6th (5th)
SS: 7th (19th)
LF: 9th (13th)
2B: 11th (9th)
C: 13th (15th)
3B: 25th (26th & below replacement player level)
SP: 9th (1st)
RP: 9th (11th)
Clearly 3B is our biggest issue, with RP'ing, C and LF as possible areas for improvement this off season. The retirement of Papi puts the DH position into the spotlight as well.
The good news: our top prospects, Beni, Moncada and Devers all play a position of need (3B and LF). Devers is too far away to influence 2017, but perhaps Sam Travis, Pablo, Shaw, MOncada or Hernandez can carry us at corner IF until he's ready. A Mix of HanRAm, Young and others might lessen the hit we take at DH with the loss of Papi.
Our rotation might not need "fixing" at all, as they have been the best in MLB over the second half. If we bring Buch back, we should have the depth we need. That leaves the pen as one big area of need. It won't be easy to replace Ziegler, Uehara and Tazawa. Carson Smith may help some, but picking up two decent RP'ers seems like the right thing to do.
One other solution might be to sign Justin Turner. He's a decent fielding 3Bman, soon to turn 32, and coming off 3 straight .800+ OPS seasons. I know that would further block Moncada and maybe Devers, if we sign him to over 2 years, but I'd prefer doing this than signing a DH. We might be able to later trade Moncada, Devers, Shaw or Pablo due to having him on the roster.