Cubs starting staff keeps rolling — maybe toward history?

ATLANTA – When Jon Lester pitched another seven innings Sunday without allowing an earned run, the Cubs’ starting rotation ascended yet another spot.

Doing what no Cubs’ starting staff has done since the dead-ball era, the five-man rotation has a 2.30 ERA through 61 games that – if it were to hold up – would rank second only to the 1918 World Series team (2.16) in franchise history. And just ahead of the 1919 starting staff (2.31).

“It’s been fun to be a part of,” said Lester, who didn’t walk a batter for the third consecutive start in Sunday’s 13-2 victory over the Braves – and joined teammate Jake Arrieta among only four starters in the majors with ERAs under 2.00.

“Obviously, the pace we’re on is pretty crazy,” said Lester (8-3, 1.89 ERA). “Hopefully, we can just stay even-keeled with it and keep going.”

Crazy?

If they come even close to keeping up this pace, the Cubs’ would have the best rotation ERA in the majors since the dead-ball era ended in 1920.

The 1981 Astros (2.43 in a strike-shortened season) and the 1968 Cardinals (2.49 the year before the mound was lowered) are the only two teams since then with rotation ERA’s under 2.50.

Only three since 1990 had sub-3.00 ERAs: 2011 Phillies (2.86), 1992 Braves (2.95) and 2015 Cardinals (2.99).

“I think the expectations have been exceeded, but it’s not really all that surprising to us,” said Arrieta, the NL’s reigning Cy Young winner. “We all know that we’re highly capable of pitching at a level like this for an extended period of time.”

And consider this: The five-man crew’s 0.996 WHIP is better than all but six individual pitchers in the majors. The only two who aren’t Cubs: Clayton Kershaw (0.646) and Johnny Cueto (0.993).

“You don’t want to be the guy that screws up, for sure,” said John Lackey (2.63), who ranks fourth on the staff in ERA – and 10^th in the NL entering Sunday.

Lackey was the top-rated starter on that Cardinals team that won 100 games last year. He said this one’s similar.

“Maybe a little bit more of a veteran presence on this team, guys with a little more of a track record with Jonny and myself,” he said, “and [Jason Hammel’s] been around, and Jake’s had a couple great years obviously. …

“You want to do well. You don’t want to let your boys down.”

Like the Greg Maddux-Tom Glavine-John Smoltz Braves staffs that used to golf together constantly and talk pitching on the course, this group does the same thing away from the field, Arrieta said.

“Whether we’re on the course or at dinner, or playing guitar in the hotel, there’s normally a baseball-related discussion in there at some point,” Arrieta said. “There’s times where we kind of want to get away from the baseball conversations. But it’s just kind of the way we’re wired.”

Lester, who pitched around four errors Sunday, said that’s as much a whole team thing as it is just pitchers.

Several of them also talk about the competition within the group. Just look at the similar performances:

• Arrieta: 1.86 ERA (second in the majors), 0.954 WHIP (fifth).
• Lester: 1.89 ERA (fourth), 0.946 WHIP (fourth).
• Hammel: 2.36 ERA (10th), 1.107 WHIP (23^rd).
• Lackey: 2.63 ERA (14th), 0.927 WHIP (second).
• Kyle Hendricks: 2.90 ERA (24^th), 0.937 WHIP (third).

“Everybody’s looking at our record and talking about run differential and how prolific the offense is,” manager Joe Maddon said. “That differential exists because the pitching’s been so good, particularly the starting pitching.

“To this point I think the starting pitching is really setting the tone for the season.”

Camaraderie? Competition? Prep work? The catchers? Obviously ability.

“I’m sure not a lot of us have answers for what’s going on,” Lester said. “Enjoy it while we can.”

Meanwhile, the Cubs also enjoy the advantage of being one of only two teams in the majors that hasn’t been forced to use so much as a sixth spot starter – never mind the seven or more starters that 22 teams have needed at this point.

Only the team the Cubs play this week, the Nationals, have been able to stick with five starters so far this season. That staff, which includes 10-0 Stephen Strasburg and former Cy Young winner Max Scherzer, ranks third in the majors with a 3.29 ERA.

“From a rotation standpoint, we’ve got the ability to pitch this way,” Arrieta said. “Obviously, the way our numbers look right now, with all of us pitching at that level, is going to going to be difficult to sustain. But there’s no reason we can’t do it.

“We’ve done it to this point,” he said. “We stay healthy and take care of ourselves the way we do, and I think it can continue.”

Chasing Franchise History

The best rotation ERAs in Cubs history (since 1913, as far back as breakdowns are available):

1918 2.16

1919 2.31

1917 2.60

1914 2.70

1916 2.73

1933 2.81

1945 2.90

1963 2.90

1920 2.92

1913 2.97

1915 3.04

1972 3.10

Chasing MLB History

The Cub rotation’s major-league leading 2.30 ERA would be the best for any starting staff in baseball since the dead-ball era (pre-1920) if they maintain it. The top five:

1981 Houston Astros* 2.43

1968 St. Louis Cardinals 2.49

1968 Cleveland Indians 2.50

1943 St. Louis Cardinals 2.54

1972 Baltimore Orioles 2.58

*-Strike-shortened season

Note: Only three starting staffs since 1990 have recorded sub-3.00 ERAs (2011 Phillies, 2.86; 1992 Braves, 2.95; 2015 Cardinals, 2.99).