[24] The Nationals made one major trade during the off-season, dealing top pitching prospects Lucas Giolito and Reynaldo López and 2016 first-round draft pick Dane Dunning to the White Sox for Adam Eaton, an outfielder with team control through the 2021 season.
[25] The Washington Post reported after the trade that the Nationals had become pessimistic after observing Giolito in 2016, including his first major league appearances, that the consensus top right-handed pitching prospect in baseball would end up developing as they had originally expected.
[26] In trading Espinosa, who was reportedly unhappy about Eaton's acquisition as it was expected to mean center fielder Trea Turner would become the 2017 starting shortstop, the Nationals acquired pitching prospects Austin L. Adams and Kyle McGowin from the Angels.
Stephen Strasburg was efficient as the Opening Day starter for the Nationals, but the Marlins took the lead in the top of the fourth inning, with right fielder Giancarlo Stanton driving in catcher J. T. Realmuto with a double and then scoring on a single by Marcell Ozuna.
The lead was cut in half as Nationals right fielder Bryce Harper hit his fifth career Opening Day home run to right field off Marlins reliever David Phelps in the sixth inning with no one on base, and then Phelps gave up the lead entirely in the bottom of the seventh inning, as pinch-hitter Adam Lind homered to center field after a two-out single by catcher Matt Wieters—both players new additions to the Nationals who signed late in the off-season, with Lind making his first plate appearance with Washington.
[80] The struggles of newly minted closer Blake Treinen in the ninth inning prompted manager Dusty Baker to announce on April 19 that closing duties would be shared between relievers Shawn Kelley and Koda Glover.
[88] The team suffered a serious blow when center fielder Adam Eaton, acquired in the off-season in a trade with the Chicago White Sox, stepped awkwardly on first base beating out an infield single in the ninth inning at Nationals Park against the Mets on April 28.
Outfielder Brian Goodwin struck his first major league home run off Athletics reliever Zach Neal on June 2, a two-run shot over the high wall in Oakland Coliseum's right-center field.
[149] In a 6–1 victory over the visiting Chicago Cubs, defending World Series champions, on June 27, the Nationals tied a franchise record for stolen bases in a game with seven, all off the battery of pitcher Jake Arrieta and catcher Miguel Montero.
[150] Four of those steals were notched by shortstop Trea Turner, who stole seven bases in the four-game series against the Cubs at Nationals Park before leaving the rubber game on June 29 after being hit in the right wrist by a fastball from reliever Pedro Strop.
[152] The injury announcement came just a day after Glover, placed on the disabled list earlier in the month with back stiffness, told reporters he had been experiencing right shoulder pain since late May and was continuing to deal with severe rotator cuff inflammation after initially trying to pitch through the issue.
St. Louis brought in reliever Matt Bowman to try to nail down his first career save, while Nationals manager Dusty Baker sent infielder Adrián Sánchez to the plate to pinch-hit in his first MLB at-bat.
[188] On July 16, the Nationals completed a five-player trade with the Oakland Athletics, acquiring relievers Sean Doolittle and Ryan Madson for right-hander Blake Treinen and prospects Jesus Luzardo and Sheldon Neuse.
[note 15] The Nationals rallied to win the second game of the series behind a revamped pitch arsenal from starter Roark, who befuddled Diamondbacks batters by ditching his four-seam fastball and mixing in a heavier-than-usual dose of curveballs.
[216] Kendrick was activated the next day, with the Nationals placing infielder Stephen Drew on the 10-day disabled list and designating minor league first baseman Matt Skole for assignment to clear a spot on the 40-man roster.
[239] The Nationals clinched a series win over the Chicago Cubs with a 9–4 victory on August 6, as although Fedde left the game after 5+1⁄3 innings in line for the loss, having given up three home runs and four earned runs in total in his second major league start, the team rallied to take the lead against Cubs reliever Carl Edwards Jr., who hit third baseman Anthony Rendon on the shoulder with the bases loaded and ended up taking the loss as catcher Matt Wieters hit the next pitch out to straightaway center field for a go-ahead grand slam.
[244] General manager Mike Rizzo said later in the day that tests showed Harper had "significant" bruising of the bones in his left knee but had avoided any ligament or tendon damage, meaning he was expected to be able to return later in the season.
[257] In a harrowing moment in the eighth inning of the next game in the series on August 26, a 9–4 bounceback victory for Washington,[258] Nationals second baseman Adrián Sánchez was felled by a foul tip into the chest after trying to bunt away a 97-mph fastball from Mets reliever Jeurys Familia that sailed in on him.
[283] Cole got the start on September 4 against the division rival Miami Marlins and earned the win in the 7−2 contest, in which Read notched his first career hit by chopping an infield single deflected off the glove of pitcher Jarlin García.
Inserted in the ninth inning as a defensive substitute in left field, Alejandro De Aza leaped to take a home run away from Marlins pinch-hitter Tyler Moore to end the game.
[note 18] Washington finished off the series with an 8−1 rout of the Marlins, their eighth victory against their second-place division rival in a row, in front of a crowd Reuters estimated at fewer than 800 at first pitch on September 6, with Hurricane Irma bearing down on South Florida and an evacuation order in place.
[286] Manager Dusty Baker disclosed that outfielder Brian Goodwin had experienced a setback while rehabbing from a groin injury suffered the previous month, rendering his status doubtful for the rest of the season.
[note 23] The Nationals ultimately took two of three from the Braves, dropping the last game of the series on September 21, although the veteran Zimmerman set a new personal best for a single season in home runs as he hit his 34th off Atlanta starter R. A.
[313] Closer Sean Doolittle suffered his first blown save as a National since being acquired in trade from the Oakland Athletics in July, giving up a single to Andrew McCutchen and then a home run to Josh Bell on his first two pitches of the ninth inning on September 28.
[359][360] Just before Game 1 of the NLDS began on October 6, the Nationals announced the indefinite suspension with pay of assistant hitting coach Jacque Jones pending a team investigation of an unspecified legal matter, the first off-field problem Washington had faced all season.
Both men had been shot on June 14, 2017, when a gunman opened fire on Republican U.S. senators and congressmen practicing at Eugene Simpson Stadium Park in Alexandria, Virginia, for the annual Congressional Baseball Game for Charity.
[384][386][387][388] As they had in the NLDS in 2012 and 2014, the Nationals faced elimination in Game 4, which took place on a damp and chilly afternoon and evening with a strong breeze from Lake Michigan blowing in from the outfield, knocking down long fly balls for both teams that might have been home runs.
After that, Cubs shortstop Addison Russell committed an error on Nationals first baseman Ryan Zimmerman′s slow roller, allowing Turner to score and giving Washington a 1–0 lead before Arrieta struck out second basemen Daniel Murphy to end the inning.
Joe Maddon had called in Cubs closer Wade Davis to get the last out of the seventh inning and kept him in to pitch the eighth and ninth in the hope that he would get a seven-out save, an unusually long outing for him.
[410] Scherzer started the All-Star Game at Marlins Park for the National League on July 11, allowing a single and striking out two, including Home Run Derby champion Aaron Judge, in one inning of work.