Rodriguez, who will take the hill on Tuesday at Citi Field, is 11-13 with a 3.76 ERA this season, and 4-4 with a 3.71 ERA in 11 appearances since joining the Pirates.
On Aug. 8, Pittsburgh was 63-47. The club now sits three games below .500 and needs to finish 6-3 to end the season with an even mark.
"It's not a rallying cry, but we're aware of it," Pirates manager Clint Hurdle said of finishing better than .500. "For us, it would be a good finish, because it will take seven wins [out of the last nine] to get to 82. It would be a very positive statement with which to finish the season."
The Pirates would have to reverse a downward trend: They are 5-17 in September.
"Shock is not the right word," said general manager Neal Huntington. "Concerned, frustrated are better words."
Rookie Collin McHugh will make his first start for the Mets since Sept. 10. In his Major League debut on Aug. 23, the right-hander tossed seven scoreless innings, holding the Rockies to two runs while striking out nine. He lasted just four frames in each of his two subsequent outings.
The 25-year-old, New York's 18th-round selection in the 2008 First-Year Player Draft, could be pitching for a spot on next season's roster. That's a common theme among Mets players seeing the field at this point in the season.
"There's a lot of guys playing for a lot of things in there -- be it contracts, be it jobs or just pride alone," Collins said. "But everybody plays for something, and I know they are. We just need to continue to battle through one of the worst times any of us have ever been through in the game."
Pirates: Pittsburgh to look at young hurlers
The Pirates will keep Kyle McPherson and Jeff Locke in the starting rotation for the remainder of the regular season. A.J. Burnett is the only veteran starter on the staff signed for the 2013 campaign. Hurdle said he wants to see the young pitchers in action to assess their value for next year's rotation.
Mets: Francisco could pitch again
The Mets aren't ruling out a return before the end of the season for closer Frank Francisco, who is dealing with right elbow tendinitis. Francisco has tallied 23 saves.
The Pirates have been outscored, 118-80, in September.
The Mets are 3-1 against the Pirates this season.