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The Nationals’ pitching staff appears to be the least of their worries as they prepare to begin the postseason. They finished second in the majors behind the Rays with a 3.34 ERA, and they have a deep bullpen with a closer, Drew Storen, rounding into mid-summer form.

But some scouts who followed the Nationals down the stretch wonder and worry if the Nationals’ pitching staff is wearing down. They saw signs of fatigue in a young staff that, aside from Edwin Jackson and Mike Gonzalez, had never pitched into the playoffs before.

Just because they perceived the Nationals to be tiring does not mean they were. That should be made clear. But it bears keeping in mind, and a few numbers seem to support the thought.

The Nationals’ starters posted a combined 4.20 ERA in September, 17th in the majors and their worst month of the season by a healthy margin. Even if you remove fifth starter John Lannan from the equation, the Nationals’ rotation still had a 4.15 ERA in the final month of the season.

Gio Gonzalez and Jackson have both thrown 200 innings in a season multiple times, but the Nationals two other playoff starters experienced a new kind of workload. Jordan Zimmermann threw 34 1/3 more innings than he ever had before, and he posted his worst ERA by month (4.41) in September.

Ross Detwiler exceeded his 2011 total by nine innings, but he threw 87 of his innings last year in Class AAA Syracuse. In his final starter of the season, Detwiler walked five as he recorded only seven outs in a blowout against the Cardinals.

Over the season, as Manager Davey Johnson worked to protect his young rotation, the Nationals’ bullpen threw 515 1/3 innings, second-most in the National League behind the Rockies, who at various times used a system that prohibited starters from throwing more than 75 pitches. That may be cause for concern on the surface, but the bullpen seems to be holding up fine.

First, Johnson did not overwork any one reliever. Tyler Clippard led the Nationals with 74 appearances, which ranked 13th in the National League. No other Nationals reliever ranked higher than 24th in appearances. Clippard’s workload was heavy for a closer – only John Axford saw more action among reliever with double-digit saves. But Clippard also saw a hefty reduction in his innings, from 91 in 2010 and 88 1/3 in 2011 down to 72 2/3 this year.

Second, the Nationals’ bullpen punched up a collective 3.07 ERA in September, eighth in the majors. Their bottom-line performance did not suggest any fatigue. Storen’s April elbow surgery now seems like a blessing in disguise. While everyone else is crawling into the playoffs, Storen has pitched less than half the season.

The Nationals’ staff will also be helped by three full days off between the end of the regular season. Some starters, especially Zimmermann, have struggled when given extra rest. But if any of them are tired, no Nationals starter will make his first starter on less than six days rest in the NLDS.

In the end, it does not seem like the Nationals have any more problems with fatigue in their pitching staff than any other team at this point in the season. But some of the scouts following them think it might, and so it’s something to watch.