Get ready for a lot of talk this fall and winter about how the National League is the better of the two leagues. It's already started: Jeff Gordon says we've, "heard lots of pro-American League blather in recent years," but "it's time to chill that chatter." Pat Caputo, in the middle of an article about what a great season the Tigers had, interrupted himself to say, "[T]he National League was better than the American League overall [in 2012], as well." Zach Stoloff seemed to say the AL is still the better league, but later called the NL "the supposedly inferior league," and claimed that the World Series is a different game, presumably one favoring more athletic, less powerful teams whose pitchers have practice hitting.
This is the tip of the iceberg. You can almost hear it coming if you take a look at this page or this page. Having dropped eight of the 13 World Series matchups from the post-strike year of 1995 through 2007, the NL has won three in a row and four of the past five; likewise, after losing an incredible 12 All-Star Games in a row (with one miserable tie) from 1997 through 2009, the NL has won three straight of those, too. The Series haven't been close, either, with one seven-game series in the bunch; since 2008, the team the postseason process has declared the NL's best has beat its AL counterpart by a total of 16 wins to nine, and outscored them 134-95.
That's still just 25 games, though (28 if you count the three straight All-Star Games, but are those even "games," really?). After the first 25 games of 2012, the Dodgers were 17-8, on pace to win 110 games (they went 69-68 the rest of the way). It's a big mistake to read much into that. Stoloff doubles down on it, noting the NL's 11-3 record at home since 2008 and calling it "a lopsided figure that clearly can't be accounted for by home field advantage." Perhaps not, but it certainly can be explained by a combination of home-field advantage and random variation.
We know we can't look at those 25 games and determine that the NL is better. For one thing, it's now less likely than ever that the best team in either league will make the Series; this year featured the NL's third-best team against the AL's seventh-best (though to be fair, the AL team had the better record in 2008, 2009 and 2011). Even if it were a large enough sample of games, it's not clear what those games are measuring, since it's so rarely the best against the best.
This is the point where we turn to the MLB-wide interleague records. After a bit of back-and-forth when interleague play began in 1997 -- including the NL dominating two of the first three years and winning four of the first seven -- the AL has won the league-wide interleague "series" with the NL in each of the last nine seasons. The disparity reached its peak in 2006, when the AL won 154 of the 252 games between the leagues. They also went 149-103 two years later. After that, the leagues seemed to be gradually leveling out -- the AL won 138 in 2009, then 134 in 2010, and was just 131-121 in 2011. This year, though, was the worst for the NL since 2008; the AL went 142-110 against the NL. That's a huge advantage for the AL. If you want to add in the World Series games from the last five years, the AL's advantage since 2008 shrinks from 695-567 all the way to 704-583 -- so the average AL team, if it got to play 162 games against the average NL team, even including the World Series beatdown, would be expected to go 89-73.
The raw interleague records aren't necessarily determinative; they can be skewed by a few very good or very bad teams (for a while, NL apologists would sometimes try to claim that the Yankees by themselves, then the Yankees and Red Sox, caused the imbalance). In 2012, the five AL playoff teams went 59-31 in interleague play; the five NL playoff teams went 40-41. The five worst NL teams went 34-59; the five worst AL teams, 45-45. From top to bottom, given their relative station within their own leagues, the AL teams performed much better than the NL teams.
The AL is still roughly as dominant as ever in the regular season, and I can't find any reason to think the NL would be better in the postseason: Skoloff's assertion that pitchers hitting gives the NL an advantage would also show up in regular-season interleague games (they get to play half those games at home, too), and his assertion that more athletic, less powerful teams have an advantage in October would carry more weight if recent (but pre-2008) history were not littered with big, slow, powerful AL teams winning World Series.
No matter what you hear over the next few months, the AL has still been the better league, and it hasn't been close. I do think there are reasons to think that advantage will be disappearing though, and quickly. For one thing, the transition to the AL of the NL's worst team -- the Astros, of course, who went 6-9 against the AL and 49-98 against the NL -- will by itself go a long way to balance things out, at least for the next two or three years, when the Astros figure to continue being terrible.
My other reason is more of a hunch: aside from Mike Trout, how many AL players aged 25 or under can you think of that you expect as much from as you do from Bryce Harper, Stephen Strasburg, Giancarlo Stanton, Jason Heyward, or Justin Upton (who I know has been around forever and has had some disappointments, but is still a stunningly talented 25)? I can't think of many. Then add the likes of Starlin Castro, Yasmani Grandal, Brandon Belt, and Anthony Rizzo to the pile, and it seems to me that the NL has a stronger group of good young players that figure to continue getting better.
So, the AL's advantage might be coming to an end, but there's been no sign of it yet. And when the big changeover does come, it won't be heralded by four to seven games in October.