[17] Janssen and McLouth joined utility infielder Emmanuel Burriss, shortstop Ian Desmond, starter-turned-reliever Doug Fister, outfielder Reed Johnson, center fielder Denard Span, left-handed reliever Matt Thornton, second baseman Dan Uggla, and starting pitcher Jordan Zimmermann in a sizable free agent class.
[24] The Nationals bid for contracts with multiple top free agents during the off-season, including Yoenis Céspedes, Jason Heyward, Darren O'Day, Justin Upton, and Ben Zobrist, but lost out on them to other teams.
[61][62] In total, Harper cracked nine home runs in April, tied for second-most in the National League behind Colorado Rockies shortstop Trevor Story and third baseman Nolan Arenado, who hit 10 apiece.
[65][74] The Nationals struggled at times on offense, posting the third-worst batting average in the National League ahead of only the Braves and Milwaukee Brewers amid poor performances at the plate from center fielder Michael A. Taylor, left fielder Jayson Werth, and first baseman Ryan Zimmerman, despite strong hitting from Harper and second baseman Daniel Murphy, an off-season acquisition who hit in 12 straight games during the month[75] and had 11 multi-hit games.
Outfielder Matt den Dekker and reliever Sammy Solis were called up from the Syracuse Chiefs, the Nationals' Class AAA International League affiliate, to replace them on the roster.
He gave up a solo home run to right fielder J. D. Martinez on the first pitch of the inning, but in the next at-bat he struck out third baseman Miguel Cabrera to set a new Montreal-Washington franchise record with 19 strikeouts.
Giolito made his first start June 28 against the New York Mets at Nationals Park, pitching four scoreless innings and allowing just one hit before a rainstorm delayed the game and prompted manager Dusty Baker to go to the bullpen when play resumed.
[127] Right-handed pitching prospect Reynaldo López was called up from the Class-AA Harrisburg Senators to make his major league debut with a start on July 19 against the Los Angeles Dodgers at Nationals Park.
[138] Zimmerman was injured again just days after coming off the disabled list when he was hit on the wrist by a fastball thrown by San Francisco Giants closer Santiago Casilla on July 31.
[140][141] The Washington Post reported that erstwhile closer Jonathan Papelbon had agreed to cede ninth-inning duties to Melancon and take up a different role out of the Nationals' bullpen.
[152] Rookie starting pitcher Reynaldo López, who temporarily replaced Papelbon on the roster, earned his first major league win that day over the Atlanta Braves in a tight 7–6 game, giving up one run over seven innings pitched.
[155] On August 22, Strasburg was placed on the disabled list with elbow soreness after a string of poor starts, and A. J. Cole was called up from the Class-AAA Syracuse Chiefs to replace him in the rotation.
[160] Rzepczynski made his Nationals debut on August 26, striking out Gerardo Parra of the Colorado Rockies before hitting Charlie Blackmon with a pitch, after which he was lifted from the game.
The team recalled Syracuse Chiefs pitchers Trevor Gott, Matt Grace, and Rafael Martin, catcher Pedro Severino, and outfielder Brian Goodwin.
[174] Rookie starting pitcher A. J. Cole got his first career win on September 2, outdueling Noah Syndergaard of the division rival New York Mets at Citi Field in a 4–1 contest.
[176] Right-hander Stephen Strasburg was activated from the disabled list to make a start on September 7 versus the Braves, but his return was short-lived, as he was lifted from the game in the third inning after experiencing discomfort while pitching.
[179] On September 6, third baseman Anthony Rendon hit his first career grand slam off Braves pitcher Williams Pérez, putting the Nationals on top in a game they went on to win 9–7.
[180] On September 9, rookie center fielder Trea Turner posted his first multi-homer game, hitting a two-run shot followed by a solo home run to walk off the division rival Philadelphia Phillies 5–4.
Nationals manager Dusty Baker took exception to the play, and when Kang next came up to bat, Cole threw a ball behind his back and was ejected from the game, leading to a benches-clearing altercation on the field.
[192] In the following game, a rain-soaked September 26 matchup with the Arizona Diamondbacks, catcher Wilson Ramos tore the anterior cruciate ligament in his right knee for the second time after making a leaping catch on a relay from first baseman Ryan Zimmerman, forcing him to undergo season-ending surgery.
[200] Catching prospect Spencer Kieboom, meanwhile, made his major league debut on October 2, drawing a walk from Marlins reliever Brian Ellington as a pinch-hitter and then coming around to score later in the inning.
[221] The game was billed as a marquee match-up between two of the best starting pitchers in Major League Baseball, Clayton Kershaw for the Dodgers and Max Scherzer for the Nationals, but neither starter was particularly sharp.
[222] Kershaw pitched five innings and held on to the lead, but the Nationals repeatedly pushed him to the brink, and his frequent discussions on the mound with Dodgers catcher Yasmani Grandal incited a chorus of boos from the crowd.
Severino doubled in the fourth and scored on a sacrifice fly by Trea Turner to reduce the Dodgers' lead to 4–3, but in the fifth, with Jayson Werth and Rendon on base, Espinosa again struck out to end the inning.
In the eighth, Clint Robinson doubled in the first postseason plate appearance of his career and speedy Michael A. Taylor entered the game to pinch-run for him, but Dodgers closer Kenley Jansen struck out pinch-hitter Chris Heisey on a called third strike to end the inning.
[227] Dodgers starter Rich Hill used his curveball very effectively for 3+2⁄3 innings, and Los Angeles held a 2–0 lead in the bottom of the third when Lobatón came to bat again with two outs and Daniel Murphy and Danny Espinosa on base.
[228] Although Roark had an uncharacteristically unsteady outing, the Dodgers were 0-for-6 with runners in scoring position during the first five innings even though they had the bases loaded with one out three times,[226] at least in part thanks to good Nationals defensive plays, notably by left fielder Jayson Werth.
Right fielder Bryce Harper then singled, scoring Werth to give the Nats a 2–1 lead, and third baseman Anthony Rendon followed that with a 432-foot (132-meter), two-run home run into the left field seats, putting Washington ahead 4–1.
[239] Washington mounted a comeback in the bottom of the seventh, when Espinosa led off with a walk and pinch-hitter Chris Heisey followed with a two-run homer off reliever Grant Dayton to cut the Dodgers' lead to 4–3.
He led all of Major League Baseball in strikeouts with 284, a Washington Nationals single-season record,[note 4] as well as in walks plus hits per inning pitched (WHIP) with 0.97 and swinging strikes (15.3 percent).