Charlie Manuel isn't the biggest fan of interleague play - and not just because the Phillies have struggled mightily against the American League.

Since 2005, the Phillies have the third-worst record in interleague play, going 30-51 for a .370 winning percentage. In the same span, the Phils have a .613 winning percentage against National League foes.

"It seems like we go into interleague play not playing good at that time since I've been here," said Manuel, who has been manager since 2005.

But it could be more than that.

When interleague play began in 1997, every team in each division played the same teams from an opposing league's division. But with "natural rivalries" sprouting up and Major League Baseball straying from its original scheduling approach, interleague play has created some imbalance in the schedule.

In 2010, the Phillies play three 2009 playoff teams from the American League: Boston (six games), along with the Yankees and Twins. They did get a break in the three-game series against Toronto being moved to Citizens Bank Park, where the Phillies will officially be the road team but have a decided home advantage.

Entering Friday's play, the combined records of the Phillies' interleague opponents yielded a .536 winning percentage.

In the NL East, the Marlins have the toughest interleague schedule (.549 winning percentage) mostly due to the fact that their natural rivals are the Tampa Bay Rays, the best team in baseball. The Nationals have the division's easiest interleague schedule (.398 winning percentage). Washington plays one team with a winning record, the Detroit Tigers.

Manuel said he was a fan of interleague play when it began because of the intrigue of bringing new teams to different cities.

"Now that it's been around for quite a while, I think sometimes the schedule can be more difficult on different teams," Manuel said. "That's not only us, that's every team in baseball. If we play the contenders in the American League more than some other National League teams and they beat us, yeah, I've got a problem with that.

"I'm sure the Braves, Mets and Marlins, every team in baseball feels the same way. That's kind of how it goes."

Some players and managers around the majors have suggested making changes to interleague play or taking a break from it. But interleague play has always resulted in a spike in attendance and TV ratings for Major League Baseball.

Said Manuel: "Surveys and things like that prove fans like it the way it is."