How will Roark bounce back from an erratic season?

As we transition into offseason mode here, we're reviewing each significant player on the Nationals roster. We continue today with Tanner Roark, who labored throughout the first half of the season but then found himself again down the stretch.

PLAYER REVIEW: TANNER ROARK

Age on opening day 2018: 31

How acquired: Acquired from Rangers with Ryan Tatusko for Cristian Guzman, July 2010

MLB service time: 4 years, 55 days

2017 salary: $4.315 million

Contract status: Arbitration-eligible in 2018, free agent in 2020

2017 stats: 13-11, 4.67 ERA, 32 G, 30 GS, 0 CG, 181 1/3 IP, 178 H, 105 R, 94 ER, 23 HR, 64 BB, 166 SO, 6 HBP, 1.335 WHIP, 2.4 WAR

Quotable: "He struggled early. He had a weird spring training with the WBC and started off slow. But we like what we saw from him tonight and what we've seen from him lately. He's coming into form coming down the stretch, and that's where we need him most." - Jayson Werth on Roark on Sept. 1

2017 analysis: Roark's year may well have been defined more by when he didn't pitch than when he did. It began in spring training, when he left camp to join Team USA's roster for the World Baseball Classic, a true honor for the right-hander. But he wound up appearing in only two games, making only one start (the event semifinal against Japan).

That seemed to put Roark behind the eight-ball when the regular season began, though things actually got off to a solid start: He went 3-0 with a 3.64 ERA in April. It actually was midseason when his season began to spiral out of control; in 10 appearances in June and July, he was 3-5 with a 6.24 ERA, letting 83 batters reach base in only 53 1/3 innings.

Roark's biggest problem during his struggles was an inability to put away batters. He'd get to two strikes, then couldn't finish them off. He finally began to trust his bread-and-butter pitch, two-seam fastball, late in the season, and that helped him post a 3.32 ERA over a stretch of nine starts.

With an added boost of confidence, Roark ended the regular season feeling better about himself. And the Nationals were prepared to start him in Game 4 of the National League Division Series. But the rainout at Wrigley Field ultimately opened the door for Stephen Strasburg to make that start, and then Roark watched from the bullpen throughout Game 5, having surprisingly never thrown a pitch in the series.

2018 outlook: This won't be the first time Roark enters a season trying to bounce back from a disappointing one. It happened to him in 2016, and he responded with a fantastic and consistent performance.

Roark will hope to use that past knowledge to help him get off to a strong start in 2018 and maintain it throughout what will be his fifth full season in the major leagues. He stands to earn another significant raise through the arbitration process, and free agency looms after the 2019 season.

Would the Nationals try to lock up Roark long-term? It's a possibility, though keep in mind he was a late bloomer. He's already 31, and he'll be 33 when he reaches free agency. How much longer does the organization want to commit to a pitcher who has been awfully good for long stretches during his career but also has struggled to maintain consistency from year to year?