"You want to be able to win a game for your new team and the guys here," Hamels said. "They've been playing outstanding baseball all season, and you kind of want to get in the mix. For them to put up the runs early, it made my job a little easier."
Contreras finished with three RBIs, while Javier Baez reached base in five consecutive at-bats and picked up an RBI in the first to raise his National League-leading total to 83.
But this game was about Hamels, and especially his changeup. He got six of his nine strikeouts on the pitch, tying for his most since his no-hitter against the Cubs on July 25, 2015.
"All year, my changeup has been horrendous," Hamels said. "That's been the focus I've had these past couple weeks is to get back to what I know I'm comfortable with. This is the reason I made the league when I was so young, is because of my changeup. That's what I had the most success on.
"Today, I was able to execute them and keep my mechanics the way I'm comfortable in doing to really let that changeup work."
Hamels even got an assist from first baseman Anthony Rizzo on hitting and pitching. The Pirates had runners at first and second with two outs in the first and catcher Contreras and Rizzo went to the mound. Contreras wanted to make sure they had the signs straight. Rizzo chimed in with pitch selection.
"I think all three of us were trying to call pitches," Hamels said. "It's good when you can get some good input from the first baseman. That's coming from a pretty good hitter when you think the same pitch and you're all spot on, it's a good feeling. He told me what to throw, and I'm on it."
In the fourth, when Hamels hit his infield single, who gets credit? Rizzo.
"Rizzo had a really nice bat there for me to choose, and I'm glad I chose right," said Hamels, who admitted his first two at-bats felt as if he were swinging underwater.
It was the lefty's first hit since July 17, 2016, when he did so for the Rangers against the Cubs in an Interleague game at Wrigley Field.
Chicago had acquired Hamels from the Rangers on Friday, and he scattered three hits and walked two over five innings, striking out nine. The only run off him was unearned. Hamels had not pitched since July 23, and he said the layoff affected his fastball command.
The fact that Hamels has postseason experience means he won't be wide-eyed as the Cubs head into the stretch run.
"He's definitely not going to be influenced or overwhelmed by anything," Cubs manager Joe Maddon said. "Just conversationally, he's a pretty solid individual. Winning an MVP in a World Series, which I witnessed [in 2008], he's pretty good. He's kind of the right fit regarding ability and personality, demeanor, experience level. Look at his stuff, and I'm watching the video and I'm not seeing [anything] different from a couple years ago.
"I know he's excited, we're excited. He could be a tremendous difference-maker for us."
MOMENTS THAT MATTERED First things first: While Hamels got his first at-bat in the first, Pirates starter Nick Kingham needed 51 pitches to get through the inning. The Cubs had runners at second and third, and a run scored on Jason Heyward's groundout. Ben Zobrist, who was on base, then tallied on an error by second baseman Sean Rodriguez, who booted Baez's grounder. Ian Happ ended an eight-pitch at-bat by getting hit by a pitch.
Then Baez showed off his baserunning skills when he broke to steal third. Kingham's throw sailed for an error, allowing Baez to score. Kyle Schwarber added an RBI single that Rodriguez had trouble fielding to open a 4-0 lead.
"It's probably the first time in my career I've had two at-bats before the third inning," said Hamels, who struck out in the first and grounded into a fielder's choice in the second.
Relief:Brandon Kintzler, acquired from the Nationals on Tuesday, celebrated his 34th birthday and Cubs debut by pitching 1 1/3 scoreless innings in relief. Instead of flying to Pittsburgh, Kintzler got in a car and took a 4 1/2-hour ride. It's only the second time this season he's pitched more than one inning. The other time was also at PNC Park on July 10. The right-hander's arrival was perfectly timed because it meant Maddon could give relievers Steve Cishek, Jesse Chavez and Pedro Strop the night off.
"That's the value of Brandon tonight," Maddon said. "We needed him to do that tonight. We stretched him out, and I think he was good with it."
Said Kintzler: "It's part of the challenge with a playoff-contending team. You've got to stretch it out." More >
SOUND SMART Hamels did not give up an earned run and struck out nine in his debut while collecting a hit. According to STATS Inc., the only other pitchers to do that in their first games after switching teams were Nolan Ryan (1972 Angels), Roger Clemens (2004 Astros) and John Smoltz (2009 Cardinals).
"He's a great competitor like we had talked about," Maddon said of Hamels. "How about running to first base? The guy's a good athlete. I thought it was a great first start for him."
YOU GOTTA SEE THIS Cubs center fielder Happ made a tumbling catch of Alex McRae's fly ball to open the Pirates' fifth and rob the pitcher of his first Major League hit. Happ had to collect himself after the play but stayed in the game. According to Statcast™, the play had a 34 percent catch probability.
HE SAID IT "This is why you put all the time in the offseason and Spring Training -- it's to get an opportunity to win a championship. Sometimes when you're not on a team that's going that direction, it's nice to jump and be put in that situation. Being in that scenario, it's always going to be energetic, and your focus zones in a little bit more. Plus, when you don't have to speculate any more -- the [trade is] done, and this is the team, and this is what I'm planning on doing, and this is where I want to go in the postseason -- to get that out of the way keeps things more lively, but at the same time, gives a good direction." -- Hamels, on feeling invigorated coming to the Cubs
INJURY UPDATE Home-plate umpire Chris Guccione took a foul ball off his mask during Heyward's at-bat in the third inning. Guccione stayed in the game and Heyward doubled. But after Baez walked, Guccione left the game and second-base umpire Ed Hickox took over behind home plate. They finished the game with a three-man crew.
UP NEXT Mike Montgomery will open a four-game series against the Padres on Thursday. Montgomery will be making his 12th start subbing for Yu Darvish, and so far he is 3-3 with a 3.50 ERA as a starter. In his last outing, he scattered a season-high 12 hits but said he felt good. He's 2-1 with a 4.93 ERA in 12 games at Wrigley Field. The Padres will counter with left-hander Robbie Erlin. First pitch is scheduled for 7:05 p.m. CT from Wrigley.