CHICAGO (AP) -- The catcher had a career day and wanted to talk about his batterymate. The pitcher was pretty sharp himself and he wanted to talk about his catcher.
And so it goes for the suddenly improving Chicago Cubs, who are developing some chemistry and winning games following another forgettable start to a season.
''Huge game,'' Hammel said in reference to Baker. ''He was the hero today, for sure - three big hits and he put down some good fingers for me, and that's pretty much all we needed.''
Baker responded in kind.
''I'm more happy about Jason being able to win again,'' the catcher said. ''He has pitched well the last few outings, so anything I can do to help out makes me happy.''
Hammel (7-5) allowed five hits and one walk en route to his seventh victory in seven decisions against the Nationals in his career.
Chicago won for the 21st time in 38 games amid speculation that Hammel and other veterans could be moved before the trade deadline.
''(The players) have been developing a personality as a team,'' Manager Rick Renteria said. ''They're having fun and getting to know each other, doing whatever it takes to play the game (the right way).''
A .160 hitter at game time, Baker capped his big day with a bases-loaded, three-run double off reliever Jerry Blevins in the seventh inning. The four RBIs matched Baker's career high for one game and doubled his season total to eight. He also had four RBIs against the Nationals on Sept. 4, 2009, in Washington. Chris Coghlan, Justin Ruggiano and Ryan Sweeney each had a pair of hits in the 13-hit attack.
Washington starter Tanner Roark (7-5) gave up four runs on 10 hits and one walk over six innings. He had won his previous four starts, not allowing more than two runs in any of them.
After Adam LaRoche launched a solo homer to right field that tied the score at 2-all in the fourth inning, Hammel retired the next 10 batters before Wilson Ramos singled with one out in the seventh inning. Reliever Brian Schlitter entered the game and induced Ian Desmond to bounce into an inning-ending double play.
The Cubs never looked back after Sweeney's two-out, two-run single gave them a 4-2 lead in the fourth inning. The hit scored Coghlan (single) and Baker (single).
NOTES: Cubs OF Junior Lake was cleared by team physicians but did not play. He reluctantly left the series opener the previous night after a head-first collision with a steel door in right-center field. President of baseball operations Theo Epstein said the organization would look into padding the doors for safety purposes. ... Each team plans to use its so-called 26th man in the day-night doubleheader on Saturday - rookie Dallas Beeler (0-0) for the Cubs in the opener and Blake Treinen (0-3) for the Nationals in the nightcap. Gio Gonzalez (4-4) will open for the visitors in the afternoon contest, while Jeff Samardzija (2-6) will get the ball for the home team in the second game. The Nationals are expected to promote LHP Xavier Cedeno from Triple-A Syracuse for the game, while RHP Taylor Hill will move down to create a roster spot. ... The Nationals are hoping that OF Bryce Harper (left thumb surgery) will return to the parent club early next week.