The story of the Twins' season has been its terrible starting rotation. The Twins have used nine starting pitchers this year, and seven of those have ERAs above 5.00. By contrast, the Pirates only have one pitcher, reliever Evan Meek, who has an ERA that high, and Meek is now at Indianapolis.
The first matchup of the series pits Scott Diamond against Kevin Correia. Diamond has been the Twins' best starter this season, posting a 2.13 ERA in eight starts, although the lefty only has 29 strikeouts in 50.2 innings and doesn't have a particularly impressive minor-league record.
The other two games will be easier on the Pirates. Francisco Liriano starts against Erik Bedard on Wednesday (7:05). Liriano isn't his former electric self, and he got bumped from the Twins' rotation after a poor start. He returned to the rotation in late May and has pitched much better since then.
On Thursday (7:05), Liam Hendriks faces James McDonald. Hendriks put up excellent control numbers in the minors, but like so many Twins pitchers of recent vintage, he's basically a soft-tosser. He's found major-league hitters tough to master so far, posting a 7.83 ERA in five starts so far while allowing eight home runs in 23 innings.