I disagree that Duran is a lost cause, but overall your commentary is valid. Duvall will be back soon, so the Sox will have 6 outfielders--Yoshida, Duvall, Duran, Refsnyder, Verdugo, and Tapia--plus Kike, who will probably stay at SS.
You hit, you play--simple as that. These are the current outfield OPS's--
Duvall 1.544
Yoshida .853
Verdugo .825
Duran .816
Refsnyder .792
Tapia .659
So it's a little early to give Duran the boot, plus Duvall isn't back yet.