Epstein, the team's president of baseball operations, told reporters Friday that the Cubs are essentially not involved in any discussions regarding possible trades after speculation surfaced that they could be chasing Baltimore Orioles shortstop Manny Machado.
"We have more than enough ability to win the division, to win the World Series," Epstein told reporters before the Cubs' 6-2 victory over the San Francisco Giants. "We really need to focus on our roster and get the most out of our ability and find consistency."
Getting things to even out when it comes to the Cubs' on-the-field product this season has remained a struggle. The Cubs are among the best in the majors in run differential but have had issues with pushing runs across the plate after hits create scoring opportunities.
Situational hitting with runners in scoring position remains a priority for Epstein -- who said Friday that the Cubs haven't "gotten the bang for our buck" -- and for manager Joe Maddon, who told reporters Friday that at times his hitters have been guilty of pressing too much.
"Everybody wants to score three or four or two," Maddon said, according to the team's official website. "Just score one."
Ben Zobrist delivered a bases-loaded double in the seventh inning when the Cubs snapped a 1-1 tie en route to taking the series opener 6-2. Kris Bryant delivered a two-out, two-run single later in the inning to make it 5-1.
After Kyle Hendricks allowed two hits in seven innings for the Cubs on Friday, Jose Quintana will start the second game of the series on Saturday at Wrigley Field. Quintana (5-3, 4.47 ERA) was dominant in his last outing against the Cincinnati Reds when he allowed one hit and four walks in seven innings and struck out seven.
Quintana is in search of his first career win against the Giants after dropping both his previous two starts against San Francisco.
The Giants, who have lost three straight games, continue to struggle on the road, where they dropped to 10-17 this season. San Francisco has lost all three games of its current road trip and have been outscored 21-5.
One bright spot for the Giants was the return of left fielder Mac Williamson, who missed a month with a concussion. Williamson threw out a runner at the plate Friday and finished 0-for-4 with three strikeouts.
Williamson was fresh off a successful rehabilitation stint with Triple-A Sacramento and told reporters Friday that he was hoping to get back to where he was before the concussion. In his first comments since the injury, Williamson characterized some days of his recovery as miserable.
"I never had one before," Williamson said, according to the San Francisco Chronicle. "I didn't really know what I was feeling or wasn't feeling. Some days I was feeling really good, and then I took the exertion test and felt awful after that. ... It was just miserable."
Chris Stratton will start for the Giants on Saturday. Stratton (5-3, 4.92) has collected victories in each of his past two starts despite allowing eight runs (seven earned) in those outings. Stratton will make his first career start against the Cubs.