Mike Rizzo has had his Adrian Veidt moment. After years and years of searching for a centerfielder that can lead-off the Nationals have found one in Denard Span. Consider for a moment that in 2010 the Nats team OBP from the lead-off position was .300 flat then dipped below .300 in 2011 rising to a still terrible .325 in 2012 while Denard Span for his career has a .357 OBP. If the Nationals had weaknesses in 2012 it was at the lead-off position and with outfield defense where Michael Morse is a -20.4 UZR/150 left fielder. Bryce Harper will improve on that and Denard Span combined with Harper and Werth will make the Nationals outfield a defensive sight to behold.
Since I am a little late to the Denard Span party here are a few links from around the web that wrap up the trade nicely from multiple perspectives.