Well, stat wise the Nats had the best 3-4-5 in the league before Hammer went down.
Putting an OBP man in the 1-2 spots would only help them.
Remember the Riggleman Creed: "We do NOT care about individual player stats and plateaus. We care only about winning."
And they weren't winning even with the most statistically amazing 3-4-5 in the league. A lack of OBP at the top are a problem, but hardly the solution. The whole line-up is completely unbalanced with no one at the top, a 3-4-5 who are inconsistent and a virtual no-mans land after that.