Acquiring Ethier at this time reminds me of when the Sox got Rios in 2009. Prior to this season for Ethier and '09 for Rios, each annually hit in the .290s with OBPs around .350 (Ethier slightly higher). The difference is that Ethier has a little more power where Rios has the ability to steal more bases. In 2009, Rios hit .264 with a .317 OPB for Toronto (108 games), while Ethier is hitting .252 with a .335 OPB this season for LAD (72 games).
I say this from a position of comparing stat and story lines, as I haven't been able to see Ethier play much this year.