But under the new collective bargaining agreement, Interleague Play is no longer a biannual event, it's a season-long event. The American League West's Angels opened play April 1 against the National League Central's Reds, and the AL Central's Tigers will close the year in September against the NL East's Marlins. There have been -- and will be more -- intriguing Interleague matchups spread evenly throughout the season.
AL teams have won 66 of the first 127 Interleague meetings this year, and with about half of the cross-league matchups in the books, now is as good a time as any to examine a few Interleague trends from the past few years and this one:
• The American League has come out ahead in Interleague Play -- currently 252 games, 251 from 1999-2000, 224 in 1998 and 214 in 1997 -- in 11 of the past 13 seasons. The National League won 129 games in 2002 and 137 (its highest win total to date) in 2003. The AL won the series handily in 2012, taking 142 of 252 games, and has won as many as 154 games (in 2006). But considering the pace of this year's series, it doesn't figure to be as lopsided -- regardless of which league wins out.
• No team is perfect in Interleague play this year, and nobody is winless, either. But a few teams come close. The Rays (9-1) and Mets (7-1) have beat up on opposite-league foes more than anyone to date, while the woeful Marlins have just one win in nine games against AL teams. Most first-place teams are somewhere in the middle of the pack: St. Louis is 3-1, Atlanta is 6-6, Boston is 2-2, Arizona is 3-3, Detroit is 4-5 and Texas is 3-5.
• The Yankees entered the year as the only team with an Interleague winning percentage above .600 (it was .603) but a 4-6 mark this year has dropped them to a measly .595. It's still far and away the best in baseball. New York is 174-118 all-time against NL teams in regular-season play.
The best all-time record in the NL belongs to the Mets who, thanks to a 7-1 mark against the AL this year, have improved to 144-123 (.539).
The Pirates entered the year as the only team with an Interleague winning percentage below .400 (it was .397) but they've since boosted it to .407 with a 6-3 mark this year. It's still worst overall in baseball.
• The AL this year inherited one of the least successful Interleague teams in when the Astros switched over from the NL. Houston carried a 107-123 mark into the season (though the Astros have played roughly 40 games fewer than most of their AL peers) for a winning percentage of .465 that placed them ahead of only the Royals and Orioles entering this season. But the last-place Astros have gone 4-3 this year against the Rockies and the Pirates, both of whom have better records.
• Justin Verlander entered the year in a five-way tie for 10th all-time with 19 Interleague wins, but the only other active pitcher among the five is Andy Pettitte (Randy Johnson, Greg Maddux and Aaron Sele are the others).
But what makes Verlander's win total against the NL so remarkable is that he's achieved it with just two losses. No other pitcher ahead of him on the leaderboard (Mark Buehrle leads with 26 wins) has fewer than eight losses. Verlander improved to 20-2 overall with a May 27 win against the Pirates, bringing his career Interleague ERA to 2.68 ERA with 9.5 strikeouts per nine innings and 1.092 WHIP in 177 2/3 innings (26 starts).
Buehrle also notched another Interleague win with a victory over the Braves on May 27, while Freddy Garcia (who has a 2.84 ERA in 295 career Interleague innings) has 25 with a win over the Nationals. CC Sabathia now has 23 with a win over the D-backs.
A.J. Burnett (22), Roy Halladay (21) and Pettitte (19) remain among the active leaders.
• Despite a down season overall, Albert Pujols continues to be one of the best hitters in Interleague play. Of course, his first 11 seasons were with the Cardinals, and now he's on the other side with the Angels. But he's managed to keep up his pace against the opposing league -- with a career .334 average in Interleague play to go with 45 doubles, 43 homers, 140 RBIs and a .605 slugging percentage in 170 games. This season, Pujols has six RBIs in nine games against the NL.
Pujols entered the year with a career Interleague average only slightly better than teammate Josh Hamilton, who is now a .322 career Interleague hitter after going 4-for-29 this season.
• A player on the opposite coast, Baltimore's Nick Markakis, boast's baseball's best Interleague average with a .348 mark. The Orioles outfielder has a .885 OPS in 115 career Interleague games, with 10 homers and 57 RBIs. He's 11-for-38 (.289) this year with a home run and seven RBIs in nine games.
• The three Interleague hits leaders all wear pinstripes, though only one has done so this season. Derek Jeter (345) and Alex Rodriguez (307) both have been sidelined by injury, while Ichiro Suzuki has moved into the No. 2 spot (with 309) thanks to seven hits.
The No. 4 and 6 men on that list -- Johnny Damon (296) and Bobby Abreu (275) -- also are former Yankees. Michael Young sits at No. 5 with 280 in his career.
• Speaking of Yankees, Mariano Rivera (with 68) entered the year with 28 more Interleague saves than second-place Trevor Hoffman, and Rivera has only increased his lead. He has four more this year (two each against the D-backs and Rockies) to also increase his lead over Joe Nathan and Jose Valverde (34), the next-best active closers.