Just two years ago, in 2014, something historic happened. The 88 win SF Giants beat the 89 win Kansas City Royals in the World Series. It was the first time in history two teams with under 90 wins met to decide who would be crowned baseball's champion. While that was a unique situation, finding one such team in the World Series is not. The Detroit Tigers in 2012, St Louis Cardinals in 2006, Houston Astros in 2005, and New York Yankees in 2000 all have made the World Series this century with under 90 wins.
Anything can happen in the playoffs.
Which is good because last night Wilson Ramos hurt himself and without Ramos and Strasburg and either Bryce or Murphy the Nats probably resemble a team that would struggle to win 90 games. Even if the injury isn't serious, it may not matter. It only has to be an injury that would take a couple weeks to heal in order to have a drastic effect on the Nationals playoff chances. Things are beginning to look very bleak.
Truth : The Nats could be losing their All-Star .307 / .354 / .496 22 HR catcher
Further Truth : That's overselling Ramos who had a first half unlike any other extended period in his career. Since the All-Star break, a time which featured at lot more rest to try to keep Ramos fresh, Wilson hit .279 / .317 / .447. That's probably more indicative of the player the Nats are potentially losing for the playoffs. Not a fringy MVP candidate, but a guy who gets All-Star consideration if he has a hot half and it's a weak year.
Further further truth : But even if they are losing that it's a big deal because the gap between that and Ramos' replacements is very large. Lobaton is near end of life as a useful back up and has hit .220 / .317 / .363 while spelling Wilson. Severino has had success in the majors but in a week of plate appearances over two years, and he was hitting an empty .271 in AAA this year.
Losing Strasburg is a blow but given the performance of Scherzer and Roark this season, and the problem the Dodgers have with LHP, it merely created a problem for one game in the NLDS. Losing Ramos would be an issue but his likely performance level was something that could be covered for. Even together it's far from a death blow for the team.
However if you add a loss of Murphy, who hasn't played a full game since the 17th, or Bryce who apparently has special x-rays that can't be read right away, that takes it beyond something the Nats can reasonably adjust for. Murphy has been their best hitter all year long. Stephen Drew has done a fairly amazing job off the bench but he can't be expected to replace an MVP candidate. Bryce, for all his issues, has been the second or third most important offensive presence for the Nats this year and is by far the most likely National to work a walk. Heisey has done yeoman's work in the OF this year with timely home runs, but he can't replace that presence in the middle of the lineup.
After having pretty even, maybe even good, luck with injuries over the course of the season, things have come at this team fast and hard. The Nats post-season comes down to the health of these players. Losing one is fine - nearly every team has their one. Losing two can be worked around. But losing three or four? That makes the Nats a different team, a team that makes one point to the variability inherent in a short series to have any real hope.