The critical decision in yesterday's demoralizing loss to the Cubs — Davey Johnson pinch-hitting for Gio Gonzalez in the bottom of the seventh with his team ahead 1-0 — was a produce of the manager seeking an insurance run and trying to give his bullpen some breathing room.

In principle, that notion makes some sense. But it requires some consistent production from those bench players who would be asked to pinch-hit in that situation. And right now, the Nationals aren't getting much production at all from their reserves.

When Chad Tracy struck out to lead off the bottom of the seventh yesterday, Nationals pinch-hitters fell to 7-for-48 on the season, a .146 batting average. Even more alarming, Nats pinch-hitter have yet to drive in a single run so far in 2013.

That comes in stark contrast to the numbers the Nationals produced off the bench last season. Pinch-hitters batted a collective .288 with four homers and 26 RBI in 2012, one of the most-productive units in the majors.

So what's happened to derail that this season? Nearly the entire bench returned intact, with Tracy, Steve Lombardozzi, Tyler Moore and Roger Bernadina taking up four of the five spots (the final one is held by whichever catcher isn't in the lineup on a given day). Those players simply aren't producing the way did a year ago, aside from one.