Top second-half storylines for the Nationals

As the second half of the season arrives, we have a pretty good idea just what the 2017 Nationals are. This is perhaps the most talented team they've had during their now-six-year run of contention, with an imposing and deep lineup, dominant starters atop the rotation and an experienced and productive bench.

This is also, of course, a team with one gigantic hole that could blow the entire thing up: a bullpen that desperately needs a midseason makeover. There's also reason to be concerned about the growing list of injured key players and an underperforming back of the rotation.

So what is left to determine over the next 2 1/2 months? Actually, there's a lot. Here are the five biggest questions facing the Nats as they prepare to return to action this weekend, win the division for the fourth time in six years and potentially do something once they get to October...

1. Can they actually overhaul the bullpen into a reliable unit?
This is the question that looms over everything, the one that simply must be addressed if the Nationals are going to have any reasonable chance of advancing in the postseason. It's also the most difficult problem to solve, because it's not like one proven closer is going to solve everything. These guys need multiple reliable arms for the back of their bullpen.

Also complicating matters: There is neither the depth of elite closers available like last summer nor the depth of teams out of contention willing to sell right now. Kelvin Herrera looked like an obvious fit back in April and May. Then the Royals got hot and went into the All-Star break 1 1/2 games out of a wild card spot. They're not selling.

In the end, the Nationals' best hope may be to acquire multiple setup-type arms (Ryan Madson, Pat Neshek, Brad Hand) who won't cost as much, then hope one or two guys emerge from the farm system (Erick Fedde, Wander Suero) and hope a couple of members of the current bullpen step up and earn Dusty Baker's trust to pitch in key situations (Enny Romero, Koda Glover, Matt Albers).

2. Can they get the lineup healthy again before the stretch run?
Not as much has been made of this, because the lineup as a whole has been exceptionally productive and the injuries have come in slow drips for the most part, but the Nationals batting order is far from full capacity right now. They're missing Adam Eaton, Jayson Werth, Trea Turner and Michael A. Taylor. That's a lot.

Obviously, Eaton isn't coming back from a torn ACL. But the other three are expected back over the course of the next month, with Werth probably rejoining the active roster first, then Taylor, then Turner. The Nationals need all three of them healthy and back to form by September, lest they want to risk anybody still trying to find his swing in the middle of crunch time.

3. Can Ryan Zimmerman sustain his All-Star production over the entire season?
It probably was too much to expect Zimmerman to maintain an MVP-caliber performance for six months. But it is reasonable to expect him to remain a potent force in the heart of the lineup, the key right-handed bat in between Bryce Harper and Daniel Murphy.

The last month, then, has been a bit concerning, because Zimmerman has looked way more like his 2016 self than his 2017 self. Since June 14, he's hitting .220 with a .267 on-base percentage, .256 slugging percentage and zero homers. That's a problem. All those hard-hit line drives from April and May are turning into hard-hit grounders, much like last season.

Zimmerman doesn't need to be the best hitter in the league in the second half. But he does need to start getting more elevation on those scorchers and start piling up more doubles and homers to keep this lineup clicking the way it has to date.

4. Can Gio Gonzalez keep it up, and can Tanner Roark and Joe Ross figure it out?
The biggest strength of the Nationals roster is supposed to be the rotation, with two aces at the top and three more above-average starters filling out the rest of the quintet. But that's not how this group looks halfway through the season. Max Scherzer has been phenomenal, even better than he was when he won the Cy Young Award last year. And Stephen Strasburg has been what we've come to expect him to be: Mostly very good, with some clunkers thrown in there.

But the 3-4-5 guys have not followed form so far. Gonzalez was the most pleasant positive surprise of the first half, posting a 2.86 ERA and putting his team in position to win almost every time he takes the mound. But lurking beneath those numbers are some familiar-looking peripheral stats. Gonzalez is putting just as many men on base as he did last year when his ERA closed at 4.57. He's been successful by pitching his way out of jams. He'll need to prove that's actually a newly learned skill and not just a fluke.

Roark and Ross, meanwhile, have been the biggest disappointments to date, for different reasons. Roark seemed like a sure thing, but he's been pretty dreadful for most of the season, with a 5.27 ERA and 1.450 WHIP. He feels like he's close to figuring it out; the Nats certainly hope so. Ross has been better at times but also has dealt with occasional diminished velocity and had to leave Sunday's start with a sore triceps muscle. We're still waiting for an update on his status, but it's certainly a concern heading into the second half.

5. Will Dusty Baker get an extension before season's end?
This question has been lurking in the background all season, but eventually it's going to have to come to the forefront. Baker is not signed beyond 2017. There's no contract option for the Nationals to pick up. There's no contract at all for 2018.

Now, there's little reason to believe the two sides would part ways given the strong relationship they've established and the success the team has enjoyed. But until anything formal is resolved, it's still going to be a lingering question. Baker has done well not to make too big a deal out of this publicly, because we've seen before what that can lead to (cough, Jim Riggleman, cough).

But if a new contract isn't offered and accepted before the end of the season, any little slip-ups by the Nationals on the field - whether attributable to their manager or not - could bring this issue to a head and create a problem.