I assume you read the post from yesterday so we can get moving on this one with little explanation. What's the path of least resistance to the Nats doing the unthinkable and missing the playoffs entirely? 96 wins is the starting point remember and you have to get to the 85-87 range in wins to "feel good" about missing the playoffs completely with 2 wild cards. (though the Angels did miss it with 89 wins that's was kind of fluky given historical precedent)
OK first we do have to adjust the win total upwards. There's just no way to avoid it. If Jayson Werth is healthy he will provide more to this team. But let's say he bounces back to a very mediocre year, something between last years showing and the injury plagued 2010. You're looking at maybe an extra 1.5 wins. So we're at 97.5 wins
Then there's Bryce Harper, even if you say he doesn't improve at all if we're lining up Span versus 2011 him and Bryce vs 2011 Morse + Bernie + other guys. He's still going to be better than that. Let's say a win better. 98.5 wins.
Ok now we can start going back down and the easiest way is through career year guys having more normal years. Adam LaRoche -2 wins. 96.5 wins. Gio Gonzalez -0.5 win. 96 wins. Ian Desmond... let's not say all the way back down to the previous year but closer than not, -1.5 wins. 94.5 wins. Denard Span, this kid bounces around, -2 wins. 92.5 wins.
We're still not there yet, are we? I guess the bullpen could be a little worse, these guys do fluctuate a bit just because they don't pitch that often. -0.5 win. 92 wins? We're getting very close to necessitating injury. I guess I'll pull out one more thing and say that catcher ends up being a complete failure with Suzuki hitting the wall and Ramos unable to recover properly. That's only another -0.5 wins though because it wasn't good last year. 91.5 wins.
Gotta stretch even more. Let's also say that Haren's bad performance was more him than injury and he somehow repeats it even though he's going to the NL. -1 win. 90.5 wins.
That's it. That's as low as I can bring the Nats without resorting to injury or a surprise crash of a season. That would likely cost them the division, but it would take some bad luck as well to miss the playoffs. The Cards got in with 88 this year and could have done it with 87.
Ok so let's throw in an injury. It doesn't have to be specific but let's say one of the big three starters go down and they are unable to pull a Detwiler out of their hat again. The replacement is terrible. -3 wins. 87.5 wins. There you go. That's a pretty decent shot at missing the playoffs with just the tiniest of bad luck.
So all they need to miss the playoffs is for everyone who had a career year to revert back to a more normal year, have three little things go bad, and suffer a serious pitcher injury all while no one improves in any significant way over last year. This should tell you one thing. The Nats aren't missing the playoffs next year without serious injury problems or surprise flameouts. Basically it would all have to go bad in "expected" ways otherwise for them to fail.
That's why I call this season a 6-month long injury watch. Lose two pitchers early and the Nats would be staring at a major problem. Throw in a major injury to a key player (Bryce, Zimm, Werth) and the Nats are probably floating around 90 wins as we see some stuff go up and some stuff go down for everyone else on the team. From there missing the playoffs isn't necessarily likely, but it could be a few bouncing balls away.