St. Louis Cardinals have the best ERA in baseball (Jeff Curry-USA TODAY Sports)

The Washington Nationals fell 8-5 to the St. Louis Cardinals Monday night.  The defeat marked the Nats’ 15th loss in their last 18 games against the Cards as well as their eighth straight loss in St. Louis (also their 19th in their last 21 at Busch Stadium) – a fitting finish for one of the team’s least successful months in years.  Washington finished August with an abysmal 12-17 record, its worst since it went 11-16 in July 2013, and the Nationals’ most losses in a month since their 11-17 record in May 2011.

[This pitch is why the Nats’ Max Scherzer was awful in August]

Although pitching was largely to blame this month (the team allowed 137 runs in a calendar month for the first time since surrendering 139 in as many games in August 2010), Cardinals pitching continues to stymie the Nationals offense.  Since mustering six runs in a game on Sept. 29, 2012, the Nats have managed two runs per game against St. Louis.  There’s a good reason they’ve struggled so mightily: baseball’s most well-groomed pitching staff.

The 2015 St. Louis Cardinals have the best record in the MLB as well as a commanding lead in the NL Central and thus have nearly clinched a playoff berth (and it’s only Sept. 1).  The Cardinals have been a dominant franchise (11 World Series, second most to the Yankees’ 27), particularly recently; they are on pace for their fourth straight division title and have clinched their eighth straight season – and 15 of 16 – with a record better than .500.

But this year, the cards have been in the Cards favor even more, especially on the mound.

Right now, the Cardinals have the best ERA (2.65) in the MLB — by a lot.

In fact, they could finish as the ERA league-leader with one of the largest margins of victory over the next-best team in the World Series era (1903-2015):

Perhaps even more impressive is that they are well on their way to becoming the first team to post a sub-3 team ERA in almost three decades – the last to do so being the 1989 Dodgers.  In fact, no team has finished with an ERA as low as the Cardinals’ right now since the 1972 Orioles (2.53) and Athletics (2.58).

The Cardinals overall pitching is clearly remarkable, and their starting rotation is a huge part of that.  Cardinals’ starters lead the majors with an average game score,  a metric devised by Bill James to determine the strength of a pitcher in any particular baseball game, of 57 in 2015.  They also lead Major League Baseball with 91 quality starts (at least six innings pitched in which they gave up three or fewer earned runs) and a 69 percent quality start percentage this season.  More importantly though, this St. Louis pitching staff ranks 13th all time in quality start percentage since 1938 (earlier data was not available for these stats). And the last two teams with a quality start percentage as good as this year’s Cardinals were the 1997 Braves and 1981 Astros.

But if we adjust for the league average quality start percentage (dividing by the league average) and put it on a scale where 100 is average (QS%+, similar to OPS+), we see that the 2015 Cardinals now rank even higher:

Diving deeper into the accomplishments of this top-quality starting pitching staff, we can examine how the Cardinals best (and most used) starters stack up against the record books.  If the season ended last night, here is how the Cardinals starters would compare to other teams in the World Series era (only pitchers with 10+ starts qualify here):

  • One of 101 teams with five or more starters that have a sub-3.00 ERA. One of seven since World War II and the first in 34 years (1981 Astros).
  • One of 19 teams with with five or more starters that have a sub-3.00 ERA and 2+ WAR. First since World War II and the first in 71 years (1943 and 1944 Cardinals).
  • One of six teams with four starters that have a sub-3.00 ERA and over 130 strikeouts. One of four since World War II and the first in 47 years (1968 Indians).
  • Currently on pace to become only team with four starters that have a sub-3.00 ERA over 150 strikeouts.
  • Only team in MLB history with five starters that have a sub-3.00 ERA and 6.0 or more strikeouts per nine innings pitched.

St. Louis relievers have been just as effective.  Although they do many things well, they specialize in closing out games.  Since a save became an official stat in 1969, only 21 teams have had a save percentage of at least 80 percent given 60 or more save opportunities.  The 2015 Cardinals are a member of this elite group (81.8 percent).

The baseball postseason often comes down to luck, but if pitching wins championships, then the Cardinals might have enough skill this year to win it all and go down as one of the best-throwing teams in MLB history.

Adam got his start with the Harvard Sports Analysis Collective and can be found on Twitter @AdamGilfix.