A look at the World Series winners over the last decade would suggest the National League has been the better of the two leagues. Since 2003, the NL holds a 6-5 edge over the American League in those critical matchups. However, even seven game series provide too small of a sample to declare which league has been best in those seasons, especially when you consider depth in addition to simply the best team.

Interleague play in the regular season has been around for 17 years, and the volume of games teams from each league play against each other provides a much better indication of relative strength. By that measure, the AL has had the NL’s number for quite a while:

The last season the NL enjoyed a winning record against the junior circuit was 2003. Since then, the AL has won the regular season 10 straight years, by as few as two games and as many as 56 games.

We’re only a quarter of the way through the 2014 season, but the NL is on top, albeit by the slimmest of margins. So far, they’ve beaten their rival league in 31 of 61 contests.

Defense seems to have been a major factor in the NL’s resurgence. As recently as 2012, teams in the AL combined to handily outpace NL teams in Defensive Runs Saved. But last year and so far this year, the NL flipped the script and has more DRS than the AL.

Through the games on May 8, the Angels (17 DRS), Royals (4 DRS), Red Sox (3 DRS) and Athletics (2 DRS) are the only four AL teams with positive Runs Saved totals. In contrast, all but four NL teams have positive DRS totals, and eight of the 15 teams in the division have at least 10 Runs Saved.