Paul Maholm is arguably not a front-of-the-rotation starter. Ian Snell is certainly not a No. 2 starter, even on the weak Pirates staff.
That's one reason why the Pirates have lost the last few games. But that may be exactly the point.
Zach Duke and Ross Ohlendorf are decidedly better than the average three and four starters, and Jeff Karstens is a legitimate No. 5. These pitchers are "coming up," bringing the Pirates to the "better" part of a still-questionable rotation.
You might think of the five starters as players of "boards" in a chess tournament. First starters typically pitch against other first starters, second starters usually go against other second starters, etc.
Paul Maholm is decidedly inferior against the Mets' Johan Santana, but Jeff Karstens may have been more than a match for Oliver Perez (too bad the Pirates didn't get to play the Mets earlier.)
Meanwhile, Zach Duke, arguably the Pirates' best pitcher right now, is playing "third board." Ross Ohlendorf on "fourth board," is actually running neck and neck with Maholm for the second best record. Jeff Karstens is at least not necessarily out of his league at No. 5.
All this gives the Pirates some reason to hope they can win all, or at least two, of the next three games.
A king once asked his top general, Sun Tzu, how to win a three-horse race bet against another king, with the stake being each man's most beautiful wife. The two kings also had three horses such that each were approximately equal to the other's equivalents.
Sun Tzu's advice: Run your third horse against the other's No. 1 in the first race and lose; your first horse against the other's No. 2 in the second race and win; your second horse will probably beat the other guy's third in the third race. Two out of three.
A relatively weak team like the Pirates may need to "invert" its pitching staff to have a chance of winning at all.