On Saturday, Arrieta struck out a season-high 11 batters and held the Pirates to three hits over eight innings in the Cubs' 8-2 win. Arrieta's stats are staggering.
• Arrieta now is 6-1 with a 0.75 ERA (five earned runs over 60 innings) in his last eight starts against the Pirates, including the postseason. He has struck out 49 while walking seven in that stretch.
• He's now given up three or fewer runs in 28 straight starts, the longest streak in the Majors since 1893.
• Arrieta has won his last 18 decisions, the fourth-longest streak in MLB history since 1913. The Cubs have been victorious in his last 21 starts, the longest streak in franchise history and tied for the fourth-longest streak since 1913.
• Arrieta is the fifth pitcher in the modern era with at least 18 consecutive winning decisions in the regular season. He joins Carl Hubbell (24-0 in 1936-37), Roy Face (22-0 in 1958-59), Rube Marquard (20-0 in 1911-12) and Roger Clemens (20-0 in 1998-99).
"It's unusual," Maddon said. "It's very unusual what he's doing."
"I feel when any ace has it going, it's tough to hit that day, and right now, he's just locked in, dialed in," Chicago's Jason Heyward said. "I feel he has a lot of pitches he can beat you with, and he can throw them in any count at any time. I don't think he throws anything straight, and it's great to have that in your arsenal."
Arrieta did run into some trouble in the fourth inning Saturday and needed a pep talk from catcher Miguel Montero to get back on track. Andrew McCutchen doubled to lead off, Gregory Polanco singled, and both scored one out later on Francisco Cervelli's single.
"He came to me and pretty much said, 'Let it go. Stop trying to hold back and guide it. Use your aggressiveness and pitch to the bottom of the zone,'" Arrieta said of Montero's speech. "That was exactly what I needed to hear."
Arrieta induced a double play to end the inning.
Think about this: The last time Arrieta gave up three or more hits in one inning at Wrigley Field was July 25, 2015, against the Phillies. That's also the last time he gave up two or more runs in an inning at home.
Arrieta was on track in the fifth, striking out both John Jaso and McCutchen looking.
"I was aggressive with my fastball down in the strike zone and got some punchouts looking with the fastball, and when I do that, I know I'm in a pretty good spot," Arrieta said.
A really good spot.
"Those pitches were -- I call them, 'Hall of Fame pitches,'" Montero said. "There's not much you can do with them."
Just ask the Pirates.
Carrie Muskat has covered the Cubs since 1987, and for MLB.com since 2001. She writes a blog, Muskat Ramblings. You can follow her on Twitter @CarrieMuskat and listen to her podcast. This story was not subject to the approval of Major League Baseball or its clubs.