Pirates vs. Blue Jays, bottom of second

Can anyone explain to me why the Pirates play the Phillies only six times in the regular season, but play consecutive series against the Orioles, White Sox and Blue Jays in June?
I enjoy interleague play, but for every Yankees-Mets or Dodgers-Angels series, there are get-togethers between teams that have little in common except their annual ineptitude.
The Pirates also entertain the Rays at PNC Park from June 27-29.
Ronny Paulino just threw out Aaron Hill trying to steal second. The throw was high, but second baseman Luis Rivas brought it down in time for the tag.
Pirates fans have their fingers crossed Duke can return to the level he reached three years ago, when he went 12-3 in Indianapolis and 8-2 in Pittsburgh. A strikeout of Rod Barajas on a changeup is encouraging.