On Sunday, after the Cubs lost to the Red Sox in Boston in the long-awaited rematch of the curse-tastic 1918 World Series, the interleague ledger for the National League Central looked like this:

Chicago Cubs


Cincinnati Reds


Houston Astros


Milwaukee Brewers


Pittsburgh Pirates


St. Louis Cardinals


The Brewers' 3-0 mark isn't technically "interleague," as their trio of victories came against the National League's Colorado Rockies. The series, however, took place during MLB's interleague schedule (i.e., the six three-game series set aside for interleague play), making it as separate from the balanced, 144-game non-interleague schedule as any matchups against the American League.

The biggest complaint about interleague play is that it drastically unbalances the schedule. Sure, many people dislike interleague because of the tradition element, but if that were its only drawback, the criticisms wouldn't have much traction (much like those directed toward the wild card). The fact is that a six-series mini-schedule where the leagues cross in such a way that each division plays another division in the opposite league (along with their designated "natural rivalries") can be nothing but uneven.

Teams play between four and six other teams they would never face regularly, and they are never exactly the same teams that their division-mates face. If one club happens to have a full slate of sub-.500 teams on its schedule while their division rival's is filled with teams ten games over .500, there is nothing that can be done; the team with the easier schedule is given a great advantage.

How have these scheduling quirks affected the National League Central? Will the division, which many predicted to finish in a tight cluster, be turned on the unbalanced nature of this year's 2011 interleague schedule? Below are the division's six teams, ranked by difficulty of interleague schedule (including the NL-vs.-NL games the various teams use to fill in the schedule).

6. Milwaukee Brewers
Opponents: at Boston, at New York Yankees, at Minnesota*, vs. Minnesota*, vs. Tampa Bay, vs. Colorado
Opponents’ winning percentage (at start of interleague): .486

Heading into the season, this interleague schedule looked like it could be the toughest of the division. The Brewers are the only team in the entire division to be stuck facing the American League East's top three teams, the Red Sox, Yankees, and Rays. It's still a tough slate. What brings Milwaukee's opponents' winning percentage down so low is the horrific record of the Minnesota Twins. At 15-27 heading into interleague season, the Twins had the second-worst record in baseball. The Brewers benefit greatly from being able to play that team six times when no other Central team does even once.

5. Chicago Cubs
Opponents: at Boston, at Kansas City, at Chicago White Sox*, vs. San Francisco, vs. Chicago White Sox*, vs. New York Yankees
Opponents’ winning percentage: .502

The Cubs are in a boat similar to the Brewers’. With the Red Sox, Yankees, and world-champion Giants on their schedule, their opponents looked to be rather formidable at the start of the season. The White Sox, however, have decided to play rather poorly this season. With six games against that .444 winning percentage—a record "bested" only by the Twins among NL Central interleague opponents—the Cubs have caught some luck. Of course, if the White Sox or Twins ever improve to anything near their preseason predictions, that luck will get wiped away.

4. Houston Astros
Opponents: at Toronto, at Los Angeles, at Texas*, vs. Texas*, vs. Tampa Bay, vs. Boston
Opponents’ winning percentage: .517

The Rays, Red Sox, and two series against the Rangers: that's certainly a much tougher draw than a team with the worst record in all of baseball would like to see. With the Royals also playing better baseball than most predicted, it's even less inviting. Astros fans can be happy that the Red Sox have yet to break things wide open (like they were predicted to) and that the team will be hosting an extra series against the Dodgers during interleague.

3. Pittsburgh Pirates
Opponents: at Toronto, at Cleveland, at Washington, vs. Boston, vs. Detroit, vs. Baltimore
Opponents’ winning percentage: .518

At first glance, Pittsburgh's slate of Baltimore, Cleveland, and Washington seems pretty easy. The Indians, however, continue to maintain the sport's top record, tipping the Pirates towards the top half of the list.

2. St. Louis Cardinals
Opponents: at Baltimore, at Tampa Bay, at Kansas City*, vs. Kansas City*, vs. Toronto, vs. Philadelphia
Opponents’ winning percentage: .519

The Cardinals suffer from the distinction of playing their interleague schedule against the most "good" teams. Of the five teams the Cardinals play, they only face one team with a worse record than Kansas City who, at the start of interleague, had a 21-22 record – the 19-23 Orioles. Every other team in the division faces at least one team with a worse record. Their interleague National League opponent also happens to be the Phillies, who own the NL's best record. Not an easy draw.

1. Cincinnati Reds
Opponents: at Baltimore, at Tampa Bay, at Cleveland*, vs. Cleveland*, vs. New York Yankees, vs. Toronto
Opponents’ winning percentage: .557

If it weren't for the misfortune of Cincinnati's "natural rival," the Reds would be much more solidly middle-of-the-pack. As it is, the Reds are forced to play six games against the best record in baseball. If the Indians really are as good as their 26-15 record would indicate, a slate of games against the Rays, Indians, Blue Jays, and Yankees will be tough to overcome for the division leader.

Pre-season predictions, here at Baseball Prospectus and just about everywhere else, saw the NL Central as a three-team race between the Reds, Cardinals, and Brewers. Today's standings show that the division is shaking out to be just that, with the Cardinals holding a two-game lead at the moment. But the interleague schedule has yet to fully start. This weekend's games were only an appetizer; the full complement of games doesn’t begin until June 17. With the Cards and Reds facing the division's toughest slate and the Brewers facing the easiest, that final, close finish could very well be affected. Based on winning percentage, the Reds’ opponents are currently favored to win 10 of the 18 interleague games. The Brewers, on the other hand, are expected to win 10 themselves. A two-game switch like that could easily mean a one- or two-place difference in the final standings if the teams stay as even as some have predicted.

The unbalanced nature of interleague play is a fact of life in today's game. Considering the effects the Brewers/Twins, Cubs/White Sox, and Red/Indians pairings have had on these rankings, it should be noted that the "natural rivalries" are the biggest reasons for this. Interleague play likely won't be going away any time soon, so it's important to recognize how the unbalanced schedule could potentially affect playoff races from year to year. If, for example, the Brewers really do gain two games on their division rivals in a tight race, they may have their very beneficial interleague schedule to thank.