In five years now as general manager of the Nationals, Mike Rizzo has approached all trade discussions with an underlying philosophy: Any move made must be in this team’s best interests not only in the short-term but especially in the long-term. That philosophy has served the Nationals well, allowing them to slowly assemble a roster and an organization built to sustain success well beyond the immediate future. But does there come a point when long-term ramifications have to take a back seat to short-term opportunities? That’s among the questions Rizzo is facing today as the 4 p.m. non-waiver trade deadline approaches. The Nationals, though assembled well enough to lead the NL East two-thirds of the way into the season, do have a few obvious areas of need, areas that if bolstered would put this franchise in better position to win the World Series this October. The biggest needs: 1) A second or third baseman who can provide more of an offensive threat than Danny Espinosa while Ryan Zimmerman recovers from a hamstring injury that more and more looks like it will keep the Face of the Franchise sidelined well into September, and 2) Another quality reliever who could take over some key innings from a talented-but-overworked bullpen down the stretch. Either would help a Nationals club that looked a bit worn down over the last week, but either also could come at a price in the form of prospects traded away or salary taken on for not only the rest of this season but for future seasons. Among the infielders whose names have been brought up: the Diamondbacks’ Martin Prado (owed about $25 million through 2016) and Aaron Hill (owed about $27 million through 2016), plus the Rangers’ Adrian Beltre (owed about $24 million through 2015, though Texas’ desire to trade him seems minimal).