Can we get over Span? The guy just isn't that good. His OPS isn't very good and certainly not worth trading for.
We're perpetually worrying about our outfield situation but it isn't bad as of this season. Harper and Morse have two spots locked down and the third sport we have a more than serviceable rotation consisting of Tyler Moore and Steve Lombardozzi with Ankiel and Bernadina sprinkled in at times. With Jayson Werth on the mend you have a deep outfield if he starts hitting well.
No to Span. If a move is made for a center fielder then it must be someone who is a clear upgrade.