Carpenter was 4-0 in the postseason last fall but hasn't pitched since winning Game 7 of the World Series against the Texas Rangers. He returns less than two months after undergoing surgery to relieve a nerve ailment that caused numbness up and down the right side of his body.
"I worked my butt off to try to get back," Carpenter said. "And it worked out."
The 37-year-old Carpenter, who won the NL Cy Young Award in 2005, will make his first start of the season Friday against the Cubs at Wrigley Field. The former 20-game winner points out he's no stranger to late-season pressure, so he doesn't mind the idea of parachuting into the intensity of a stretch run.
Health permitting, he could get three key starts before the regular season ends.
"I've pitched in games that matter," Carpenter said. "So I'm going out there with the same focus, the same program. Hopefully, I can help give us maybe a little push, and we can get on a little run."
St. Louis (80-70) has been solid on the mound but displays a mostly spotty offense. The team features five hitters with 20 or more homers - a franchise first - but the Cardinals will score eight or nine runs one day and then seem lifeless for days. It's a frustrating scenario for rookie manager Mike Matheny, who said he doesn't have to remind his team it's time to get going.
"There's nothing that even needs to be said. It's plain as the nose on your face, what we've got left ahead of us and what we have to do," Matheny said. "It's not like there's a secret, there's a formula.
"We've got to push. We've got to play our best now."
The Cardinals are hoping Carpenter can bolster an already-strong rotation. Kyle Lohse (15-3, 2.71 ERA) is one of the National League's best starters, Lance Lynn (16-7, 3.79) appears to be back on track, Adam Wainwright (13-13, 3.97) has had a solid first year back from elbow reconstruction and Jake Westbrook (13-11, 3.97) has had dominant stretches.
Plans going forward will depend on how Carpenter holds up against the Cubs (58-92). There will always be room for him, though. He is 95-42 since 2004, a .693 winning percentage that's the best in the majors during that stretch.
"Obviously, Carp's one of our leaders and an outstanding pitcher," slugger Matt Holliday said. "If he's 80-90 percent of what he usually is, we'll be in good shape."
Heading into surgery in late July, Carpenter had been hopeful of returning next season to fulfill the final year of a two-year contract. Not long after the procedure in Dallas, the right-hander began aiming for a more immediate comeback.
"As we got going and saw that my arm strength was coming back, everything was coming back and I felt good, and there was no risk of hurting anything up there, we said 'Why not try it? See if we can get back here in time.'
"Fortunately it worked out."
Carpenter threw 95 pitches in a second simulated game, and hopes to be able to pitch deep into his debut. Equally important, he recovered nicely.
"I know it's a simulated but it's still 95 throws and I felt good, felt strong, felt strong at the end and I recovered well," Carpenter said.
Carpenter began traveling with the team a few trips back, helping him regain his footing as a leader in the clubhouse.
"I still speak my mind and say what needs to be said," Carpenter said. "It's hard to voice your opinion and say things when you're not around them all the time. I've been around these guys the last month or so all the time."
The Cubs appear to be a favorable opponent for Carpenter's debut. He's 11-6 with a 3.05 ERA in 25 career starts against them, and his win total is tied for first with three others for the most against Chicago since 2004.
Carpenter has also been dominant against the NL Central, going 51-23 with a 2.98 ERA.
The Cubs will counter with Chris Volstad (3-10, 6.26), who will try to help the team snap a four-game losing streak.
Chicago has won four of the right-hander's last five starts, but Volstad has struggled with his control during that stretch, walking 19 in 27 innings. He walked four while yielding six runs and a career high-tying 10 hits in 4 2-3 innings of Sunday's 13-9 victory over Pittsburgh. Volstad had won three of his previous four outings following a 24-start winless stretch.
He has lost both of his starts versus St. Louis this season, surrendering four runs and six hits in six innings each time.
The Cubs, losers of eight of 14 to St. Louis in 2012, will need to sweep this three-game set to avoid dropping the season series for the second straight year.
The Cardinals completed a three-game sweep of MLB-worst Houston and won their fourth straight with Thursday's 5-4 victory.
Commentary at The Cardinal Nation blog: "Are expectations for Carpenter too high?".