A month ago, as baseball was just finishing up the All-Star break, the Nationals looked to be in a pretty good position. They were 48-39, sitting atop the NL East, and were expecting a host of quality reinforcements from the disabled list. The team hadn’t quite lived up to pre-season expectations, but a lot of that could be chalked up to health issues, and even their somewhat disappointing first half had them in first place; with some of their best players rejoining the club, the second half looked promising.

At that point, our projections gave the Nationals an 85% chance of winning the division. In the first 30 games of the second half, however, well, just take a look for yourself.

Since the break, they’re just 10-20, and they now find themselves 4 1/2 games behind the Mets in the NL East; their chances of making the postseason are down to 31%. They’ve lost six straight on their current west coast road trip, and now sitting at a game under .500, questions are starting to get raised about whether Matt Williams even makes it to the end of the season as the team’s manager.

So, how has this second half, and potentially the entire season, gone so wrong?

Here’s one starting point.

Aside from Bryce Harper, Jordan Zimmermann, and Denard Span, these eight guys essentially represent the core of the Nationals roster the last few years, and last year, the team got a whopping +28 WAR (using the RA9 version for the pitchers for this exercise) out of those eight players. This year, those same eight players have combined for replacement level performance, and while injuries have certainly dragged down this group, they’ve mostly been terrible even when on the field.

Werth has a wRC+ of 48 in nearly 200 plate appearances. Ramos is at 67, even though he’s been healthy. Desmond is at 81, Zimmerman at 82, and Rendon at 85, turning what looked like maybe the league’s best infield into a group that has hit about as well as you’d expect from a group of utility infielders. That’s how, despite having the best hitter in baseball this year, the team still has a wRC+ of 93. If you remove Harper’s +6.9 WAR from the team’s position player total, the remaining Nationals hitters have combined for just +5.4 WAR, which would rank 29th in baseball this year.

Of course, every team would look worse if you took away their best player, but the degree to which Harper has carried a sad sack of underachievers cannot be understated. And that’s been one of the primary problems in the second half, because Harper’s power has waned a bit since the All-Star break, and his post-break 143 wRC+ isn’t enough to offset the miserable performances of his teammates. Harper single-handedly kept this offense afloat for the first three months of the season, but you can’t expect a guy to run a 210 wRC+ all year long, and Harper’s inevitable cooling off has made it all too obvious that no one else on the team is hitting their weight.

But the Nationals weren’t supposed to be an offensive juggernaut. This roster was built to score enough runs to win a bunch of games behind an elite pitching staff, only they haven’t really had that either, at least not in terms of results so far. With a 90 FIP- that is tied for fifth best in baseball — and not that far off the Cardinals, Cubs, and Astros, all tied for the top spot at 88 — they have still flashed the traits of a very good group of pitchers, but their 100 ERA- is tied for 15th. When you combine average run prevention with a struggling offense, you get a team trying to claw their way back over .500 in August.

The primary underachievers, relative to their own fielding independent numbers, have been Strasburg and Gonzalez; their 4.14 combined ERA is over a run higher than their 3.11 FIP, as they’ve collectively given up a .347 BABIP in their 200 innings pitched. Both pitchers have historically produced results a bit worse than their peripherals, but nothing to this extreme, and if you’re looking for good news, this is probably the team’s best chance for significantly improved performances down the stretch. It’s unlikely that Strasburg and Gonzalez really are lousy pitchers, and if their results start to line up with their track records, and their own underlying peripherals, the team’s pitching staff should improve down the stretch.

With Max Scherzer and Jordan Zimmermann throwing well, and Strasburg and Gonzalez having the potential to throw well, this still looks like one of the best rotations in baseball, even with Doug Fister apparently broken and banished to the bullpen. Joe Ross has filled in pretty well in the fifth spot, and should be able to give the team a solid option to fill out the rotation before he reaches his innings limit. Overall, the team’s pitching staff still looks like a group you’d want to bet on going forward, and patience may prove to be a virtue while waiting for these guys to turn it around.

On the offensive side of things, though, there are more legitimate reasons for concern. Werth’s collapse has likely been driven by his wrist injury, and those tend to both linger and make it extremely difficult to hit for any kind of power, which is likely why he’s running an .086 ISO and a .216 BABIP this year. When Denard Span comes back from the DL, it isn’t clear that Werth should keep his starting job over Michael Taylor, who isn’t a great hitter either, but at least provides elite defense to justify his spot on the field.

Benching a high-paid veteran like Werth for a rookie like Taylor — whose defensive value would probably be ascribed to his pitchers anyway, since the results would show up in their ERA and not in his batting line — is an unlikely move, especially for a manager on the hot seat. But while the Nationals don’t have a lot of options for upgrading their roster beyond just hoping that previously good players remember how to play well, the front office could decide to make a managerial change.

While I continue to believe that we don’t really know how to evaluate managerial performance that well, there isn’t a lot of evidence that Williams is bringing strong positive contributions to the club. He’s a poor in-game strategist, his players are almost universally underachieving, and through his nearly two years at the helm, there have been a lot of rumors of clubhouse dissent. While no manager can snap his fingers and make guys like Rendon or Werth play well by sheer force of will, Williams might be the most replaceable in the organization, and if the team doesn’t turn things around quickly, pressure to “do something” will only grow.

Firing Williams isn’t going to be a cure-all, and the track record of the players on the team suggest that these guys are capable of playing well even if a change isn’t made, but it’s starting to get to the point where you wonder if making a change that isn’t clearly harmful is worth doing just to try something different. I don’t think changing managers is a panacea, but with the Nationals 2015 season unraveling before their eyes, it shouldn’t be immediately dismissed, especially since Williams isn’t helping the team in any obvious way.

Washington’s season isn’t over yet; there’s still six weeks to play, and as the last month has shown, performances can swing wildly over any small sample. The Mets could still collapse. The Nationals underachievers could all catch fire and the team could surge back into the division lead. There’s still the core of a good team here, and with a little bit of positive regression from some of their still-talented players, the Nationals should could still make a run at a 90 win finish.

But the last few weeks have made that the unlikely outcome now. A disastrous month of August has put them in a hole, and they can’t afford to dig it too much deeper. If the Nationals don’t turn things around in the next week — their next six games are against the Rockies and Brewers, two of the worst teams in baseball — it might be too late, for both this season and for Williams managerial career.