Parnell, though, might be preparing for another first in his next outing: It could be his first big league start.
The right-handed reliever, who has primarily been used as a setup man this season, was stretched to three innings by manager Jerry Manuel in the victory. After the game, Manuel indicated that a move to the starting rotation isn't out of the question.
"That is a consideration, and that was part of the plan today going forward," Manuel said. "That's a part of why we did what we did today."
Parnell was a starter throughout his Minor League career, making 92 starts in 94 Minor League appearances. Since being called up to the Mets late last season, though, all 59 of his appearances in the big leagues have been out of the bullpen.
In the Minors, Parnell owned a record of 27-30 and a 4.04 ERA.
His outing immediately prior to Wednesday lasted two innings and 33 pitches on Monday against Arizona. It was the longest in terms of pitch count for Parnell this season. He nearly matched that on Wednesday, throwing 30 pitches to complete a career-high three innings.
"I knew it had been mentioned before," Parnell said of the possibility of starting. "I try not to entertain it right now. I take it one day at a time, and I'm in the bullpen right now."
Parnell had one of his best performances of the season out of the 'pen on Wednesday, allowing just one hit in three innings to the Cardinals. He struck out three and, just as importantly, didn't walk a man. Twenty-two of those 30 pitches were for strikes.
Parnell had walked 12 batters in his previous 19 2/3 innings, during which he compiled a 6.41 ERA.
"I needed to be more aggressive in the zone, and that's what I was able to do today," Parnell said. "Today was definitely a stepping stone for me."
His performance at the plate, however, may be more memorable for Parnell. In his first big league at-bat, Parnell fought off three two-strike pitches from Brad Thompson before lining a single into left-center field. He said it was the first time he had picked up a bat since the relievers took batting practice at Fenway Park in late May. He did not mention, however, his career 3-for-32 experience at the plate in the Minors.
"I just swung," he said afterward.
He was spared the potential embarrassment of running the bases when Angel Pagan homered to center field behind him. Parnell could take his time and didn't have to worry about the speedy Pagan on his back.
"That was probably the best thing," Parnell said. "I didn't know how to get to second or third."
Tim Britton is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.