Ok so even though I do this every year I guess I should clarify some points. I don't factor in injuries beyond what I think is a reasonable playing time estimate. "Healthy" doesn't mean "100% completely healthy, playing 154-160 games" but "the most reasonable expectation of health given age/recent history". Still given that, it generally that means a full season of playing time, outside a few players (Zimm, Werth). I am a little more conservative with pitchers so I won't go 200+ innings for Strasburg, rather 170ish.
This isn't really scientific, more about general feeling. How good can the Nats reasonably expect to be if nothing really surprises in a negative way, and vice versa? Then how can we get to the nightmare or dream scenario from there. So on Wednesday I kind of felt it out and the Nats can be say in the 94 win range without having any major positive surprises (or negative ones). Not quite where I'd like them to be for an easy division title. Let's flip things around now.
We generally stick to the assumptions made with injury returns and replacements, assuming they were fair and not positive. Looking at it I can only see one place that might have been a bit positive which was Roark replacing Zimmermann. Like I said Zimmermann's year wasn't all that great but Roark was a little disappointing last year. I could see a fair assessment matching ZNN but also coming in under it. So knock a half-win away. 92 wins.
Then we get to the "plays a little better/worse" expectations. I think we can probably pull that half-win away from Rendon that we gave him here (remember we are being on the negative side of fair) keeps him around league average at 3B. 91.5 wins. We can also go ahead and pull a half-win from Ramos/Lobaton who I liked to stay same, since they are trending down. 91 wins. I don't feel fair taking from Strasburg since it was mostly a inning increase thing, or taking more from Espy (right now at least). Oh I could take from Gio too, who surprising not only arrested his fall but got a little better. 90.5 wins.
Now we get to some bigger disappointments that would still not surprise me. I took 1.5 wins from Bryce and 1 win from Max before. This still made them MVP worthy and in the Cy Young discussion. But you could probably fairly pull another win from Bryce and a half-win from Max. They were that good last year that they can fall alot and still be good. Bryce would still be in the MVP debate (just probably wouldn't win it). Max would still be a likely All-Star. That's not bad! It's good! And it's another 1.5 wins lost. 89 wins.
Anyplace else to cut fairly? I could probably assume that the bench isn't much better. I gave them a win and a half, instead let's give them just a half. 88 wins. And the bullpen could get no better. 87 wins. Oh I forgot about Trea. Yesterday in the comments I kind of bumped the positives up a win for him. Let's say a half-win up instead. 87.5 wins Any other place that would be a fair take before we get into other things? Werth was so bad last year and he's 37 so you can probably justify him barely being worth playing this year even without injury. Not a negative mind you, and not where I'd bet, but a tiny positive and in the realm of possibility. Take away a win 86.5 wins. We all know Espy can be terrible, We saw it in 2013 and 2014. Let's knock off a win there. That's still better than most #5s I bet. 85.5 wins. I still think we could knock another half-win at least from Roark. Hell, I'm trying to get down here let's make it a win. 84.5 wins. I guess maybe Ross regresses a little and Gio gets back to falling? Another win... 83.5 wins. Hmmm... maybe Revere/Murphy could get a half-win worse combined? They've been pretty consistent so it's not fair to knock them too much.
I think I've hit my floor at 83 wins. Nothing surprises here but basically everything is on the wrong side of fair. Werth doesn't come back. Rendon is merely ok. Espy was kind a fluke. Roark is just rotation worthy. Max and Bryce come back to Earth. Gio, Ross, Ramos, all slide a little. The bench, the pen, Stras, Zimm, Murphy, Revere, don't get any better. There isn't any single event here that jumps out as unlikely, but the combination of all of it going in that direction is.
Can I get to .500 from here without injury? Sure. Roark completely flames out and they never get a good 5th starter. That alone would do it from here. Or Bryce could "struggle" and merely be All-Star good. Or Werth could be flat-out done. Or Trea Turner could give the Nats nothing. There are ways.
So the Nats range of possibility is pretty large in my opinion, from like 83/84 to 93/94 wins. That doesn't mean I think they'll win 88-89 wins, just that this is the "no surprises, no injuries" range for the team. It's pretty variable to begin with. Toss in the youth involved (Ross, Turner, Taylor, Rendon maybe, Bryce - though really how much better could he be?), the injury returnees (Rendon, Zimm, Werth), the age issues (Werth), the potential career years (Scherzer, Bryce), and the intangibles and the inherent variability of the pen and bench, plus the usual crashes and soars of a baseball season and you have a team whose fortunes fly all over the place. Could it all come together and the Nats have a team like 2012 or 2014? I can see that. Can the Nats have a couple key injuries and have a team that finishes below .500.... That's a little tougher given the competition in the NL East, but if say the Marlins surprise, ok sure.
Where do I put the Nats? Well no official prediction until Spring Training is over (it'd be stupid to do that - guys can get hurt). I think I like the Nats for about 91 wins or so. But like the previous paragraph said that's a very weak bet. I have as little confidence in knowing how this season will play out as I've had in years.