I am not sure I would go so far as to say that Harper is a great player who teammates can't stand but I do get the sense that he is something of a flake with manageable eccentricities.
I don't think there is any way that the Nationals can get reasonable value for Harper back in a trade. They ought to really double down on trying to win in it all 2017-18 and then totally gut the team '98 Marlins style in 2019 and rebuild.
I don't know how much stock to put into this but for a long time, many have thought that it's a foregone conclusion that he'll be a Yankee in 2018. Big money, grew up a Yankee fan (though not from NY), made a very publicized visit to Monument Park when the Nationals last played there.