What makes it even worse is that there's a racial component here.
It's not racial. You are making something out of nothing. Harper wants to play CF over Span mostly because he wants to play CF. If Zim were capable of playing 3B year round and not making everyone tense up and hold their breath everytime he threw to 1B, and Harper's statement was to put Span in LF and play himself in CF, would that make you feel any better?
Harper shouldn't have said what he said, but honestly the thought has to be in the fore front of many people's minds. Span is a good player. There isn't anyone who comes close defensively to him, but there is a log jam of REGULAR outfielders on this team, much like the Dodgers had. Span's defense in CF isn't enough to play him over the bats of Zim, Harper and Werth (slump non-withstanding) as the replacement in CF isn't a slouch in CF either.
Espinosa can't hit but can defend. His bat is worse than Span's, but he also is playing a position where there is little to no depth on the team. Granted, you have to role with the best offense and right now Span is in there, but this "issue" should be brought up this month as the deadline gets closer. Zobrist would be a very good fit for this team atop the lineup and playing 2B. It's a shame to say that Span would be benched or flipped as personally I'm a big fan of his, but ultimately with the outfield the Nats have, Span would have to sit.