CHICAGO -- The Cubs' starting pitchers are on an historic pace, with all five ranked among the top 20 in the National League in ERA. This is the deepest the team has gone into a season using only five starters since 2003.
Consider that the Chicago starters have had 31 outings of at least six innings while giving up zero or one earned runs -- including Friday, when Jake Arrieta threw six scoreless innings in a 6-0 win over the Pirates. Since 1913, the season high for the Cubs in such outings is 65, set in 1963, according to baseball historian Ed Hartig. The 2.62 ERA of Cubs starters is the best mark of any club since 1972.
What's going on? Reason No. 1: The Cubs have adopted a holistic approach.
"We've learned a lot as an organization, just being together and how our system works," pitching coach Chris Bosio said. "We've found some things we can do to create better matchups, if you will. When you really jump into the numbers -- and it's a point of emphasis for us -- what you try to create are the best matchups for our guys. The answer is yes, we have done a couple things differently."

The Cubs aren't altering their rotation against certain teams, but making sure they take into consideration different factors. For example, John Lackey goes from Busch Stadium, which has a lot of foul territory, to a tight ballpark like Wrigley Field. How can the Cubs set up the defense to help Lackey? Does he need to change his pitch selection to get batters out?
The secret weapon may be coach Mike Borzello, who compiles the scouting reports.
"He's very, very intelligent and very smart," Kyle Hendricks said of Borzello. "It's helped me a lot with different pitch sequences, and going out to the game feeling I'm prepared with a few different options to attack each hitter. Last year, I was prepared and I'd watch video, but I also had these mechanical things in my head so I wasn't solely focused on the task at hand out there."
Each of the Cubs' coaches contribute to Borzello's report. They take nothing for granted.
"Everybody utilizes [the scouting reports] as a resource," Arrieta said. "You'd be dumb not to. That's what [Borzello] does -- he watches video all the time, he reads swings, he breaks hitters down. He deserves a lot of credit for the way we go after lineups."
Reason No. 2: The starters are fearless.
"We have no reason to be fearful of anything," said Arrieta, the reigning NL Cy Young winner. "We're what, 2 1/2 months into the season? And we've all shown the ability to have a lot of success consistently thus far. I think that breeds more confidence.
"The mindset going out there is [the starters] seem to be in attack mode from the get-go and trusting their stuff. That's kind of what happens when you have that mindset. You have guys with good stuff, who know how to pitch, who learn from each other."
Hendricks said that confidence is linked to being well prepared.
"If you trust in your preparation and your talent and what you've done to prepare yourself, if you can trust in that and believe in that, obviously, you'll be confident and pretty fearless out there," Hendricks said. "For me, having all these different options and being prepared with [Borzello] before I go out there -- even if my stuff isn't that sharp, I know I can use my other pitches and use my other weapons a lot more than I did last year. I'm throwing my curveball more and my four-seam more, which helps me not be so perfect with my two-seam and my changeup."
Reason No. 3: No one wants to be the weak link.
"It's literally just, 'Pass the baton,'" Jason Hammel said. "Do your work, and then the next guy will come in and do his work and we'll keep going."
Arrieta and Jon Lester have been steady, ranked second and third in the NL in ERA behind the Dodgers' Clayton Kershaw.
"They're dominating," Hendricks said of Arrieta and Lester. "When we have those two guys at the top of the rotation, and then you get competitors like Lackey and 'Ham' behind them, they don't want to let up. I'm trying to learn from all these guys and do my thing and develop myself into the pitcher I want to be."
The Cubs' pitchers push each other.
"We know what's at stake and we can see how we're doing so far and we know we can maintain this throughout the year," Hendricks said. "Everybody's just really pushing each other."
They also find time for fun. Part of Hammel's pre-start routine includes playing football the day before he pitches. Strength coach Tim Buss will throw passes to the right-hander, who runs routes in the outfield.
And, as boring as this sounds, the Cubs starters are taking it one day at a time.
"If I was 14-0 with a zero [ERA], that's great, but we're still in the spot we are -- needing to come out the next day and win a ballgame," Arrieta said. "Collectively, the numbers we have, that's why we're playing as well as we are. ... We confide in one another and understand our roles and guys have been executing on both sides."
And it's working.