Is this the greatest pitching staff of all-time?

I was talking to a Cubs fan who lives in St. Louis, and she complained despite how well the Cubs are doing, the Cardinals are "unstoppable." I said it wasn't such a sure thing, what with the injuries to Holiday, and Wainwright, and...

"Cardinals fans always say that," she replied.

I think there's some truth to that. Maybe it's just midwestern modesty, or maybe we just worry about angering The Baseball Gods, but I think we as a tribe sometimes dwell too much on what's not working rather than appreciating what is. I feel like I've spent most of this season talking with fans about Reynolds lack of production or Skinny Yadi's vanishing power. When someone points out that the team has the best record in baseball by it's-not-even-really-close, one of us just shrugs and says "the pitching's been good."

But the pitching has been soooo good. Like, "Children under 17 not admitted without parental supervision" good.

As of today, the Cardinals staff ERA of 2.58 would be the 6th lowest total since the dead ball era. It is the lowest any team has posted since 1972. And when you consider it in the context of its era, it is even more impressive. Let's just take that 1972 season: The Orioles finished (that slightly strike-shortened season) with a 2.54 ERA. But they were only one of seven teams with a sub 3.00 ERA, and the league ERA was just 3.26. The MLB ERA for this season is 3.88, and the nearest team to the Cardinals is the Mets, more than half a run higher, at 3.22.

Now you might be saying, "but Ben, ERA is a flawed statistic." Or, as Fangraphs puts it, "ERA is a rudimentary metric designed to assess how well a pitcher has prevented runs in the past." So let's dig just a little deeper.

ERA- adjusts for park factor and league average, making it a better metric for comparing between teams and eras. The Cardinals current ERA- is 69. (snicker) That's 31% better than league average, and the best ERA- since the dead ball era.

So, when we consider park and league, the Cardinals ERA performance is even more impressive. But there's still that whole problem with "earned runs," where some guy (or gal) rather arbitrarily absolves the pitcher of responsibility for certain kinds of mistakes made by fielders, but not other types of mistakes. So let's leave this whole notion of "earned" runs out of it.

In terms of just straight-up runs allowed, the Cardinals have only given up 349 this season. The fewest in MLB history (over a full season) was the 472 given up by Bob Gibson and the '68 Cards. (Gibson only gave up about five of those.)

The 2015 Cardinals are almost exactly on pace to tie the 1968 Cardinals for the fewest runs ever allowed. So when we say this team is geared toward run prevention, it's a bit of an understatement. They are preventing runs on pace with the greatest pitching staff from a season universally dubbed "The Year of the Pitcher."

So, you know... the pitching's been pretty good. (Also: The defense.)

Now, like Fangraphs noted about ERA, I've been focusing on how well the pitching staff prevented runs in the past. These metrics aren't so good at predicting how well the team will do in the future. So what's the overall forecast for the remainder of the season?

The Cardinals will still be very good, probably even the best in the league, but not quite as stratospherically good as they have been thus far. While their 2.58 ERA is miles ahead of the rest of the league, their 3.29 FIP - while still the best in baseball - is much closer to the pack. And if you're looking for one number screaming out for some regression, the Cardinals 80.9% left-on-base rate is currently the highest in the entire history of baseball, going all the way back to 1871, when batters could still request a high or low ball.

It's not like we haven't realized this is a good pitching staff. But I feel like we maybe haven't quite clocked just how good it is. Sure, we might well see a little regression over the final month-and-change. Instead of being right at the top of some of these metrics, they might wind up just very near the top. But when we can legitimately compare them to squads like the '68 Cardinals, the '72 Orioles... this is a historically great pitching staff.