The Nationals have claimed the NL East title in each of the last two seasons and four of the last six. That recent history plus a strong returning roster made the Nats heavy favorite to once again prevail in the division. 

Well, we're almost ready to flip the calendar to May, and Washington finds itself at 12-16. Since they're on the slate for Monday against the Pirates (PIT-WAS preview), that means they'll end the month either three or five games below .500. Whatever the case, it'll be their worst monthly mark since August of 2015 and their worst April since 2009, when the Nats went on to lose 103 games. 

So what's happened and what might the road ahead hold for the Nats? Let's take a quick look with some Things to Know about all of that ... 

1. The Nationals' playoff odds have taken a big hit.

As our own R.J. Anderson pointed out, the Nationals have lost the most points off their preseason playoff odds. They're still favorites to be a part of the playoff fray since it's still relatively early and they project well. However, they've lost more than 20 points off those number since Opening Day.

2. Injuries have surely played a role. 

They've gotten vintage-level performances from Max Scherzer and Bryce Harper, which is obviously a great starting point. However, injuries have made it hard for the Nats to get a lot of supporting value around those two core contributors. Daniel Murphy has yet to play in 2018. Anthony Rendon's on the DL with a toe injury. Adam Eaton hasn't played since April 8 because of a bone bruise in his ankle. The bullpen has also been hit hard by maladies. Speaking of which ... 

3. The bullpen has struggled. 

While Sean Doolittle has done his job and then some, the remainder of the D.C. relief corps is off to a rough start. The offense is fourth in the NL in wOBA, which assigns proper value to every possible offensive event that happens while a batter is at the plate. The rotation not surprisingly ranks fourth in the NL in ERA. Washington's fielders rank second in the NL in defensive efficiency, which is the percentage of balls in play that a defense converts into outs. 

That, of course, leaves the bullpen, which presently ranks 12th in the NL in ERA and 12th in FIP (Fielding Independent Pitching), which is scaled to look like ERA but reflects just those outcomes that have nothing to do with fielding -- i.e., strikeouts, walks, and home runs allowed. They could certainly use Joaquin Benoit (forearm strain), who recently began a throwing program. They also need Brandon Kintzler and Ryan Madson to pitch more in line with expectations, which is certainly possible given time and a larger sample. In any even, the bad bullpen has "helped" the Nats this season go 1-8 in games decided by a single run. That, though, made oddly portend better days ahead ... 

4. They've played better than their record. 

That grisly record in one-run games has a lot of bad luck baked into it, and that may correct itself in the days and weeks to come. For instance, the Nats' run differential of plus-3 means they've essentially played like a .500 team at that level. Now let's peer a bit more deeply using the BaseRuns system available at FanGraphs. BaseRuns attempts to model a team's run-scoring and run-prevention capabilities at the granular level -- i.e., on a plate-appearance-by-plate-appearance basis and with the effects of hit "sequencing" removed. Basically, it's a measure of how good a team is at controlling the fundamental outcomes of the batter-pitcher encounter. It yields what a team's record should be based on core skills. By those standards, the 2018 Nationals ought to have a record of 16-12. That's quite different from their actual mark of 12-16 and constitutes a hopeful sign going forward. 

Right now, the SportsLine (@SportsLine on Twitter) Projection Model still projects the Nats for 93.4 wins and a division title. That assumes better health and realization of these underlying trends. Partially offsetting all the optimism, though, is that the remainder of the NL East looks much tougher this year -- the Mets, Phillies, and Braves all look like potential contenders. Last season, for instance, the Nationals were the only winning team in the division. In 2015 and 2016, just the Nats and Mets finished above .500. Not since 2009 has the NL East housed three winning teams, so it hasn't been this tough in the East for a long time. 

5. And don't forget the mounting pressure. 

This coming winter, the Nationals are faced with the free agent losses of Harper, Murphy, Gio Gonzalez, Matt Wieters, Madson, Benoit, and Jeremy Hellickson. Scherzer will be going into his age-34 season. While Trea Turner and Stephen Strasburg are in place for years to come and Victor Robles and Juan Soto are on the way, the Nats figure to be in much worse near-term position starting next season. Throw in the fact that they essentially ran off Dusty Baker after he guided them to 192 wins in two seasons, and the club really needs to get it done this season before a forced pivot comes their way. Those macro issues aren't going to be keenly felt in the clubhouse on a day-to-day basis, but all of that surely isn't lost on rookie skipper Dave Martinez. 

The 2018 Nationals were always going to be judged on whether they could advance to the NLCS or beyond, but first they have to get to the postseason. They still look like real contenders to get there, but April put a dent in their hopes. The Nats need to get to their level pretty soon.