In the first part of our look at interleague play, we found that in addition to its abject loathsomeness, interleague ball may have had an affect on ten playoff spots in the last eight years. But it gets worse, when we look at how well each team's performance in interleague games reflects their overall performance.
I looked at each teams record in interleague games and in all games for each season. Then I ran a query to see how well they correlated. The answer was "somewhat" (coefficient of 0.500).
However, when I considered the fact that one influences the other, I re-ran the query with each team's interleague record and non-interleague record. The numbers got worse (coefficient 0.354).
It gets even worse when you look at the numbers per season for all teams:
There's no consistency from season to season. Of course, the way the interleague schedule was made up (or perhaps happenstance) may have something to with that. Maybe some would say it's a sample size issue. Whatever you call it, it explains why the Phils took two of three from the O's this weekend.