When the Washington Nationals have had any success at the plate lately, they've generally been able to win.
Arrieta has delivered a pair of outstanding outings at Wrigley Field since being traded from Baltimore, and he'll try to continue that trend Wednesday night against the Nationals.
The Cubs got Arrieta (1-0, 0.69 ERA) from the Orioles last month in a four-player deal that sent Scott Feldman to Baltimore, and the early returns on the right-hander - who was once a top prospect - have been good.
Arrieta held Milwaukee to two hits and a run as he debuted for the Cubs (54-71) on July 30 while starting one game of a doubleheader. He was back in the minors until Friday, when he held the Cardinals to two hits and struck out seven over seven innings of a 7-0 win at Wrigley.
"That's what I'm capable of," Arrieta said. "It's just a matter commanding the ball and limiting my walks. That's really what's gotten me in the past was too many free passes, letting guys get away when I'm in favorable counts and pretty much keeping my foot on the gas and staying on the attack.
"I've made a conscious effort to get better at certain things and it's starting to show."
Arrieta had a 5.46 ERA in parts of four seasons with Baltimore, the second-highest in the majors of any pitcher to throw at least 350 innings since he initially came up in 2010.
"For me, there's no question that this change of scenery and this trade was huge for me in my career - not only for me, but for the Cubs as well," Arrieta said. "I couldn't be more excited to be here and I'm thankful to the front office for wanting me and bringing me into this organization."
Washington (61-64) had lost four of five before Tuesday's 4-2 victory, when it finally got some hits with runners in scoring position. The Nationals had been 7 for 49 (.143) in such situations over their previous five games before going 4 for 14 on Tuesday.
Washington has won the last seven times it's scored at least four runs and lost its last four when putting up three or fewer.
Bryce Harper is 0 for 11 with runners in scoring position over his last nine games, but he's been getting on base lately. He's 6 for 12 with two doubles and two walks in his last three games after getting two hits and scoring a run Tuesday.
The All-Star outfielder's recent surge may continue since he's 10 for 23 (.435) with five extra-base hits - two homers - and seven runs in seven career meetings with the Cubs.
Harper is also 4 for 5 with a double off Arrieta.
The Nationals will counter by activating Ross Ohlendorf (2-0, 1.85) from the disabled list after shutting down rookie Taylor Jordan (back) for the season.
Ohlendorf suffered right shoulder inflammation during a relief outing in a loss at Detroit on July 31.
The right-hander allowed four runs and 13 hits in seven innings over a pair of starts during a rehab stint in the minors.
He's 1-0 with a 1.38 ERA in two starts with the Nationals this year, and is 2-0 with a 2.75 ERA in six career starts versus the Cubs. However, he has a 5.06 ERA in three visits to Wrigley Field.