Improbably, the patchwork starting staff has turned into an area of strength.
Vance Worley might be the biggest surprise of the bunch, and he'll try to deliver his third straight stellar start - and make a case for staying in the revamped rotation - Thursday night when the Pirates kick off a four-game home set against the New York Mets.
Cole had yet to take a step forward from his impressive rookie season before hitting the disabled list June 8 and Liriano took a serious step back from his outstanding 2013 before joining Cole three days later, but their absences still seemed to leave the Pirates' rotation in turmoil.
Pittsburgh (39-39) had a major league-low nine wins from its starters through May and a 4.55 ERA that was second-worst in the NL, but the rotation has turned a corner despite its injuries. The Pirates posted just 23 quality starts through their first 60 games, but they've had 14 in their last 18 after Charlie Morton bounced back from a three-run first to hold Tampa Bay scoreless over his final six innings in Wednesday's 5-1 loss.
Two of those have come from Worley (1-0, 1.98 ERA), who threw seven scoreless innings at Miami on June 15 and held the Cubs to three runs over 6 2-3 in Saturday's 5-3 victory. Combining his two major league starts with his seven in Triple-A this season, the right-hander has struck out 52 and walked five in 58 2-3 innings.
Yet with Cole returning Saturday, Worley - who posted a 7.21 ERA in 10 starts for Minnesota last season - may not stick in the rotation.
"The fact that he was able to clean up some things - revisit, I think, the delivery, the mindset from when he was having success. To feel that again, and then just start over," manager Clint Hurdle told MLB's official website. "Start with a new organization, clean chalkboard."
Worley, who spent his first three years with Philadelphia, hasn't had a lot of luck against the Mets (36-42). He has a 6.87 ERA in eight starts, the most recent of which - a one-plus inning, nine-run disaster April 12, 2013, with the Twins - was the worst of his career.
Mets second baseman Daniel Murphy is 12 for 17 with two walks against Worley.
New York's offense put up 25 runs during its sixth three-game winning streak of the season heading into Thursday, but for a sixth time it failed to extend a streak to four. Oakland scored six times in the first two innings off Zack Wheeler and went on to win 8-5 - a rare misstep from a rotation that had posted a 1.64 ERA over the past seven games.
The Mets will try to bounce back as Daisuke Matsuzaka (3-1, 2.68) faces the Pirates for the first time. The right-hander, who will be making his sixth start, was solid in his latest outing, limiting the Marlins to just a first-inning run and making it through 5 1-3 in Saturday's 3-2 loss.
"I knew that was the only run I could give up," Matsuzaka said. "So I had that in mind the rest of my outing."
Matsuzaka should have Juan Lagares behind him in this contest as the center fielder comes off the DL after a ribcage injury that's kept him out since June 1.
The Pirates again may be without left fielder Starling Marte, who passed a concussion test after a collision at second base Tuesday night but has a stiff right middle finger that's limiting his ability to throw.