As I talked about last year, seasons are usually made or broken by things you didn't plan for. Players either suprpassing expectations or falling well below them. Taking a look at if your team had more "luck" when it comes to these things can be one more piece to figure out where to set expectations for next year. Ok you can just use the pythagorean record*, that pretty much does the same thing, but I like to take it a bit deeper.
*If you must know - based on the Nats runs scored and runs allowed the Nats were "expected" to win 78 games. Their adjusted standings (at Baseball Prospectus), which tries to adjust even further for the level of competition faced and take out things like the randomness of clutch hitting, pegs the Nats at around 79 wins. So they seemed to be right on target in 2011.
EXPECTED / FORSEEABLE
Bench was terrible. CF was a huge mess. Pudge couldn't hit. Espinosa and Ramos held their own in year 1. Ian Desmond struggled for relevance at the plate. Lannan, Livan, Marquis, Gorzelanny all pitched as expected. Stockpiled bullpen arms were good. Strasburg good upon return.
Mike Morse - While you might have pegged Morse as a big contributer to the Nats in 2011, nothing about the previous three years screamed .300 30 HR hitter. (.303 and 31 to be precise). The Nats really lucked out here when you think about it, because a healthy LaRoche could have very well regulated Morse to part time duty for a good part of the season.
Clippard - Clippard is a very good relief pitcher, but dominant seasons like he had this year don't come around often. Just look at last year. The ERA leaders (70 IP) were Brian Wilson (1.81), Tim Stauffer (1.85), Heath Bell (1.93), Daniel Bard (1.93), and Jonny Venters (1.95). This year their ERAs were 3.11, 3.73, 2.44, 3.33, and 1.84, in a year when offense continued to decline. Clippard will still be good going foward but this is a lightning in a bottle year.
Zimmermann - Jordan came back from injury and pitched better than he ever had before sporting a 3.18 ERA and 124 ks in 161 IP. Watching ZNN in 2009 there was certainly a feeling he could be this good, but he could be a tiny bit wild and was homer happy leading to an ERA in the mid 4.00s. Improvement to say a 4.00 ERA in an injury return year would have been great. To do this well in 2011 was well beyond anything that Nats fans could have hoped for.
The results from Detwiler, Milone, Peacock - Generally when you bring up young pitchers, they struggle, especially if they aren't the "can't miss" Strasburgs of the world. Milone (3.81 ERA), Detwiler (3.00 ERA), and Peacock (0.75 ERA) seemed to do fine. Scrape the surface of the fancy stats, though, and you'll see that they should have given up more runs than they did, (for example - Peacock allowed 13 base runners in 12 innings, didn't K people like you think he would - only 4 - and gave up a ton of fly balls. His xFIP was 6.27. Yet he only gave up 1 run. This is called "pushing it")
Rotation health - every pitcher the Nats had this year gave them pretty much every start you'd expect. Lannan 33, Livan 29 then shut down for youth at year's end, ZNN 26 then shut down innings limit, Marquis 20 then traded. Starter health goes a LONG way toward team success.
LaRoche goes down - The Nats brought in damaged goods. The good-field, good enough hit Laroche only squeaked out a quarter season of awful baseball before going under the knife. It didn't end up killing the Nats thanks to Morse, but the typical Laroche year is better than what Nix put out last year. They definitely lost something at the plate (not to mention the field)
Zimmerman's missing time - Ryan Zimmerman is a key player for the Nats. He can't miss a lot of time without it hurting the team. He missed 60 games this year.
Werth crash - Despite the fact we all know he was overpaid, no one could have predicted it would have gotten this bad, this quickly. The guy hit .282 / .380 /. 506 the past 4 years. Even for those that "knew it was coming" because he only hit great in Philly, his away numbers in 2010 were .266 / .371 / .457 and that was the worst year he had on the road in the past 4. .232 / .330 / .389? That came out of nowhere.
What does this mean? Most likely the pitching could suffer a bit while the hitting bounces back, but there's a lot of caveats here. For the pitching, there should be an injury concern and whichever of D/M/P makes the rotation could struggle. But it's not this years rotation that this is happening to, it's 2012's, the one that includes Strasburg. And while Zimmermann's 2011 might have been lucky, a repeat in 2012 wouldn't be. As long as that injury doesn't happen to Strasburg or ZNN the rotation should be in about as good shape as this year and could be better even with less luck. Bullpens tend to have off years and great years, so that's a crap shoot but at a base level I'd expect them to be at least average tilting better.
For the hitting you'd expect a bounce back from off-years and injuries to key players but it could swing wildly. Think about this - Morse hits .275 with 23 homers, Werth has another off year, Zimm get injured, Espinosa and Ramos both regress a little, LaRoche is no good anymore. Anything unexpected or unlucky here? No, and the hitting would collapse to about worst in the league. Now think about this - Morse hits .290 and 28 homers, Werth bounces back, Zimm plays 150 games, Espinosa and Ramos both improve a litte, LaRoche comes back as gives a decent year? Again, nothing unexpected or out of the world lucky here, but now your looking at an offense that's... well it's middle of the road to top third, but that's a big improvement.
Twist my arm and I'll repeat what I said - pitching will suffer a bit while hitting bounces back - but that's not a strong bet to make. THe pitching part is based on the Nats having a near perfect year on the mound in 2011 avoiding bad luck, and the hitting is based on 6 key players all of whom who could have wildly divergent results in 2012 without anything surprising happen. Better to wait to see what they do in the offseason and see if that clears things up any.