With the dust still clearing from the Cubs' blockbuster deal with the A's, Jake Arrieta will take the mound for Chicago on Sunday with a business-as-usual approach.
The trade -- which sent starting pitchers Jeff Samardzija and Jason Hammel to Oakland -- immediately thrusts Arrieta atop Chicago's rotation. But the right-hander shouldn't have any issues adjusting to the role of ace based on what he accomplished in 39 1/3 innings last month.
Through six starts in June, Arrieta posted a 4-0 record, a 0.92 ERA and a 0.69 WHIP while holding opposing hitters to a .157 batting average and striking out 48 with six walks. In his past two outings, he's been especially dominant. Against the Reds on June 24, he opened with six perfect innings in a win. Against the Red Sox on Monday, he had a no-hitter through 7 2/3 innings.
As the Cubs continue to build for the future, Arrieta has emerged as a rock-solid part of their foundation.
"He's found his routine, he trusts his stuff, he's matured as a pitcher," pitching coach Chris Bosio said. "He's had opportunity. Coming into Spring Training, he had some physical issues going on with his arm, and we backed him off and started over again. He's an intelligent pitcher with great stuff, works his [butt] off.
"He's very deserving of how he's been pitching."
The Nationals, meanwhile, are playing for right now, and they will send Jordan Zimmermann to the hill as they try and claw their way back into first place in the National League East.
Zimmermann's numbers in the month of June were spectacular. The right-hander compiled a 1.43 ERA and a 0.82 WHIP in six starts last month. In his last outing, Zimmermann surrendered two earned runs on seven hits in six innings against the Rockies to earn his sixth win.
Nationals: Espinosa working to improve against lefties
Second baseman Danny Espinosa is consistent as a right-handed hitter, going 18-for 66 [.273], but he continues to have problems from the left side of the plate, hitting .196 with 75 strikeouts in 179 at-bats.
Why is Espinosa more successful from the right side of the plate?
"When he starts to swing from the hitting slot, he is more free [from the right side]," hitting coach Rick Schu said. "Left-handed, he has got a little longer path to get there, so he is more consistent right-handed."
Schu said he is not frustrated trying to fix Espinosa's left-handed swing, and he believes there is a lot of potential in the swing.
"You know in this game, if you try too hard, it's counterproductive," Schu said. "He wants to do so well. He is a hard-nose player. He tries too hard then tries to add more, so the swing gets a little long. … He has a chance to be a really good player and be in the big leagues for a long time."
Cubs: Epstein hopes this is Cubs' last year as sellers
Cubs president of baseball operations Theo Epstein has been in rebuild mode since joining the Cubs in October 2011, and he dealt two starting pitchers in '12, and again last year.
Epstein dealt two more starting pitchers this weekend, packaging Samardzija with Hammel for three Minor Leaguers -- Addison Russell, right-handed pitcher Dan Straily and outfielder Billy McKinney. The Cubs will also receive a player to be named later.
"We certainly hope this is the last year we'll be obvious sellers at the Trade Deadline," Epstein said Saturday. "Nothing would make us happier than being in the position Oakland is in, which is to aggressively add to the big league team and enhance the team's chances of making the postseason and winning the World Series."
The Cubs now have eight of the top 100 prospects on MLB.com's list, and four of the top 15 in Javier Baez (No. 6), Kris Bryant (No. 8), Russell (No. 11) and Albert Almora (No. 15).
• The Nationals have made just three errors in 27 games dating to June 7. They yielded just two unearned runs in June to set a new club mark for fewest unearned runs allowed in a calendar month.
• Starlin Castro has a .290 average and 98 hits. He ranks second among all NL shortstops in both categories, trailing only Colorado's Troy Tulowitzki (.350 and 99). Additionally, Castro's 38 extra-base hits are the most among Major League shortstops.
Erik Bacharach is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.