With the disparity in talent between the American and National Leagues, it seems almost unfair that interleague play lasts as long as it does, as it can influence pennant races in both positive and negative directions. Sometimes a team has a natural rivalry that just isn't fair — for instance, the powerful, well-run New York Yankees get to face the bumbling, cross-town Mets multiple times each year, while the Boston Red Sox get to face the National League's World Series representative, the Philadelphia Phillies, twice.

That isn't the only example of an unbalanced interleague slate, so today what we plan to look at is just which teams have the easiest and most difficult interleague schedules, and whether or not those differences could have any impact on a pennant race.

To do this, third-order win percentage was used, which is found at Baseball Prospectus in the adjusted standings. With standard winning percentage, there's a chance that a team is playing better or worse than they should — it does not always reflect a team's true talent level. For instance, Pittsburgh has around six wins more than they are supposed to right now based on their runs scored and runs allowed, so if I were to use standard win percentage, they would receive credit as a tougher opponent than they actually may be. After finding the third-order win percentage, I made a simple chart that shows each of the 30 teams' opponents and their adjusted winning percentage. The win percentages for each opponent were added together, which gives you a basic strength-of-schedule list for interleague play — the bigger the number, the tougher the opponents (SoS is strength of schedule; the average SoS was 3.000):

ARI 3.501
TOR 3.326
HOU 3.285
PHI 3.275
BOS 3.248
SEA 3.240
FLA 3.231
BAL 3.194
NYN 3.182
LAA 3.114
MIN 3.074
LAN 3.056
KCA 3.022
OAK 3.015
TBA 3.005
SDN 2.998
MIL 2.969
COL 2.964
ATL 2.925
PIT 2.921
CHA 2.884
CLE 2.881
NYA 2.843
SFN 2.793
DET 2.793
CHN 2.740
SLN 2.737
WAS 2.710
CIN 2.628
TEX 2.452

he Arizona Diamondbacks (.445 third-order win percentage), who already find themselves 6.5 games back of the division lead (and 5.5 out of the NL Wild Card) have by far the most difficult schedule for interleague. They kick things off with Toronto (.565) this weekend, draw the Cardinals (.563) in the NL vs. NL matchup, then have to take on Boston (.570), Detroit (.549), New York (.644) and the Rays (.609). The beauty of baseball is that anyone can win any one game, but with a calendar like that the D'backs are going to have trouble climbing out of the NL West cellar.

The Texas Rangers (.505), who are currently in first place in the AL West (up four games on the second-place Athletics) have the easiest schedule and it isn't even close: they face the Cubs tonight (.502), then the Brewers (.449), their toughest challenge, the Marlins (.535), then draw Houston twice (.334) and the lowly Bucs once (.298). They face the two lowest teams via these adjusted standings, and get to face one of them in two separate series — there's your example of a natural rivalry at play in the race for the playoffs.

The Yankees have it easy compared to the Rays and Red Sox, and based on third-order win percentage they don't need the help, as they are tops in the league. Boston has it rough, drawing Philadelphia (.575) twice as well as the Rockies (.566) and San Francisco (.570). Toronto has played well, and gets to play Arizona first, but then has to face the Rockies, Padres (.607), Giants, Cardinals and Phillies, giving them the toughest draw amongst AL East clubs.

As of this morning, Detroit and Minnesota were tied for the division lead in the AL Central — Detroit has the upper hand in interleague play, as they have the sixth-easiest schedule of any club, while the Twins have to face a slightly above average grouping. In a division that could come down to just a game or two, that's a big deal — Detroit's third-order win percentage right now is .549 while the Twins are at .537, so things are close as can be.

Philadelphia and Florida are separated by four games already in the standings in the NL East, and both clubs drew short straws when it came time for schedule making. Atlanta is just half-a-game back of the Fish, and has a much less imposing series of matchups, so interleague could be time for them to gain some ground. Washington has two things going for them as they attempt to remain relevant in the division race: they are currently a .500 level team in both the real world and in the adjusted one, and they have Stephen Strasburg on the way, most likely in time for the later interleague series if rumors are to be believed.

Fans of the Reds and Cardinals may both be upset about the other's interleague schedule until they realize that both of them have it easy; half-a-game separates them in the standings now, and no unfairness in scheduling is going to separate them further.

Out in the NL West, the Giants are the lone club with an easy schedule, as the Dodgers find themselves well above the average, while the Rockies and Padres find themselves near the middle. The Rockies may not appreciate that as they attempt to get back in things, but at least the Padres currently rank third in third-order win percentage — presumably they should be able to handle this average set of matchups.

Love it or hate it, interleague is here, and as you can see from the scheduling differences, it could have a major impact on multiple playoff races. That's great if you're a fan of the Rangers, but don’t expect fans in Oakland to react with the same kind of joy given the imbalance.

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So not only do the Blue Jays get one of the toughest (after Baltimore) divisional schedules, they also get a tough intra-league workover. But what about the rest of the intra-leauge schedules? Maybe it's more even this year, but in the past teams played teams in their league's other divisions a varying number of games. Can you look at this also? Maybe it could be added to the items listed on your statistics page, and updated daily as opponent's records change.
Fortunately -- at least for the interest of serious fans -- there's nothing to keep the supposedly resurgent Nats from tripping over the supposed doormat Orioles as happened Friday night. Even paper matchups have to be validated.