They're going to trade for a reliever. Just a question of whether it is a rental or a controllable guy, and whether it is one or two. Yeah, they will have help from the rotation in October but that will really just be one guy replacing Alvarado, and right now the entire back half of the pen seems a little wobbly [and is only three-deep not four].
If you trade Ranger this deadline it will be for someone who helps this team win this season [i.e. an unexpected bat] not to get a better return compared to the QO comp. There is not going to be any white flag, though I reckon they may quietly claim the market wasn't there for bigger moves when the payroll is just as big a factor.