Interleague play between the American and National Leagues is complete for 2012, and the American League won more games.
I could have written that same sentence here every year since 2004, had Baseball Nation been around for all those years, because the AL has now won interleague competition for nine straight seasons. It wasn't close this year -- the final tally was AL 142, NL 110 -- and it hasn't been close in most of the other eight, either:
2011: AL 131, NL 121
2010: AL 134, NL 118
2009: AL 138, NL 114
2008: AL 149, NL 103
2007: AL 137, NL 115
2006: AL 154, NL 98
2005: AL 136, NL 116
2004: AL 127, NL 125
Some will say the leagues are balanced because in those same eight seasons, the National League has won half of the World Series. Obviously, a seven-game series cannot compare to hundreds of regular-season games among 30 different teams (and the Cardinals nearly lost last year's Series). So why is this happening? Is the AL really that far superior? And why?
Some will say it's because the AL has the designated hitter. It's true that AL offenses, in general, score more runs than NL offenses, and AL teams can attract top free agents such as Albert Pujols and Prince Fielder, because those players know that if their defensive skills weaken over time, they can still contribute at DH.
That can't be the only reason, though; the AL winning percentage combined over the nine years is .558, which would translate to 90 wins in a 162-game season, enough for a playoff spot most years.
Some of this can be attributed to the Yankees and their high payrolls -- something the NL cannot match. Overall since interleague play began in 1997, the Yankees are 170-112, a .602 percentage; they have had a winning interleague record for 14 straight years and are 26-10 the last two years.
Conversely, the Chicago Cubs -- despite two playoff seasons since 2007 -- are 38-52 in interleague play during that stretch, and even with a 97-win season in 2008, were 6-9 against the American League that year. But it's not just the bad teams having a tough time in interleague series; even some of the NL teams with top records this year had losing records against AL teams (Reds, 7-8; Dodgers, 6-9; Giants, 7-8). Just three AL teams (Indians, 8-10; Royals, 8-10; Mariners, 8-10) had losing records this year in interleague play, while 10 of 16 NL teams couldn't break .500 against AL teams.
A Sporting News article from 2011 suggested the AL has tougher pitchers, since they have to face DH-filled lineups every day, and that NL pitchers, not used to this, suffer when they have to face nine hitters instead of eight and a pitcher.
Whatever the reason, what we do know is that the entire concept is going to change in 2013 when the Astros move to the American League. Instead of being confined to one weekend in May and a two-week run in June, interleague play will be scattered throughout the season, because with two 15-team leagues, the schedule will have to include at least one interleague series at all times. There might still be a stretch when more interleague series are scheduled, but MLB has not yet figured that out -- nor even whether the current number of interleague games will remain, or whether that number will be increased.
Whether the AL will continue to dominate in future years, then, with interleague play spread out, is anyone's guess. Another X-factor is whether the NL will adopt the DH or not; if the DH is made MLB-wide, that could even out the competition.
Regardless, we have reached the end of one era in interleague play with one league in utter dominance of the other-- whatever 2013 brings, there's no doubt it will be different.