Dozier is a top 5 second baseman when things are going well (and I think technically year to date as well, though I haven't looked), so you're right that he may be better than Polanco will ever be. I don't think that means keep BD. My 2 cents. BD is under contract for 2 more years, at least one of which will be at best a pretender type season (perhaps last season's outcome is likely the best we can hope for). Polanco is under control for 5 or 6 more seasons. He has the ceiling to be a top 5 2B, though he will probably be more an OBP guy than a power guy (which given the team needs right now is probably a better fit). He will almost definitely be worse than BD next year, but that investment should pay into a nice career in MN and allow for above average production at 2B when BD is most likely hitting his decline. He also has that whole out of options issue going for 2017. With that case weighed, I think you maximize BD's value and get a nice spec or four to help other areas of the team, most notably catching and starting pitching.