This. Do we really want to... bring in a veteran presence in 2015 when the next group of prospects - Sano, Rosario, Hicks, Arcia, etc will have more experience and can join Dozier, Plouffe, Mauer, Diamond, Hendricks, Perkins, Parmelee and Revere. Now is the time to trade veterans like Span, Liriano, Morneau and eventually in August Pavano and Capps. Use guys like Casilla and Valencia as sweeteners for trades now.
I personally would like to see Span traded to the Nats with Casilla for Lombo Jr., and 2 of Robbie Ray, Kylin Turnbull, and Daniel Rosenbaum. Lombo is young enough to start at 2B now, batting second after Revere and versatile enough to become an outstanding utility guy when Rosario is ready for 2B. Ray, Turnbull and Rosenbaum are 3 lefty starters due to be ready for the rotation in a couple of years.
Count the assumptions in this post.
1. Sano, Rosario, Hicks, Arcia, etc will mature into big league above-average 3rd baseman, 2nd baseman, outfielder, and outfielder. Unlikely at best.
2. A speedy low-power outfield of Hicks, Arcia and Revere cuts it in 2015 AL.
3. The Nats don't pull a trade before the end of the year and, A. are still interested in Span despite his concussion issues, B. are shopping Lambordozzi, C. Span is a worse outfielder than one of Hicks, Arcia, Revere, etc. D. Lombo is a better utility guy than Casilla
4. The Nats are interested in soaping up Morneau's contract, and A. would additinonally trade prospects on top ie. 1 or more of Ray, Turnbull and Rosenbaum
That my friend adds up to a sandcastle in the sky. Things change faster than you may think. And the Nats are changing as fast as any team in the league. They need a CF but that is all you have accurately described, I think