CHICAGO, ILLINOIS - SEPTEMBER 14: David Peterson #19 of the Chicago Cubs delivers a pitch against the Atlanta Braves at Wrigley Field on September 14, 2026 in Chicago, Illinois. (Photo by Michael Reaves/Getty Images) Getty
SEATTLE, WASHINGTON - AUGUST 23: Manager Craig Counsell #11 of the Chicago Cubs looks on against the Seattle Mariners at T-Mobile Park on August 23, 2026 in Seattle, Washington. (Photo by Steph Chambers/Getty Images) Getty
The Chicago Cubs already know they will be playing postseason baseball.
Now comes the difficult part for manager Craig Counsell.
Chicago clinched its second consecutive playoff appearance with Thursday's 2-1 victory over the Miami Marlins . The Cubs will open the Wild Card Series on September 29, but exactly how Counsell will construct his rotation remains unsettled.
One pitcher who has quietly forced himself into that discussion is David Peterson .
Peterson is scheduled to start the second game of Friday's doubleheader against the Boston Red Sox , giving the veteran left-hander one final opportunity to strengthen his October case.
GettyCHICAGO, ILLINOIS – SEPTEMBER 14: David Peterson #19 of the Chicago Cubs delivers a pitch against the Atlanta Braves at Wrigley Field on September 14, 2026 in Chicago, Illinois. (Photo by Michael Reaves/Getty Images)
The Cubs acquired Peterson from the New York Mets in June after injuries created serious questions in their rotation. At the time of the trade, the 30-year-old owned a 6.09 ERA in 16 appearances with New York.
His season has looked much different lately.
Bleed Cubbie Blue noted that Peterson entered this week with a 1.65 ERA and 18 strikeouts over his previous three starts, covering 16.1 innings. Two of those outings came against teams headed to the postseason.
Peterson then allowed just one run over six innings while striking out seven against the Cincinnati Reds on September 20.
MLB.com's latest Cubs postseason projection lists Matthew Boyd , Clay Holmes and Kevin Gausman as the most likely starting trio. However, the report described the pitching plan as being written "in pencil." Gausman is also being monitored after injuring his non-throwing shoulder against Miami.
Peterson suddenly has an opening.
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GettySEATTLE, WASHINGTON – AUGUST 23: Manager Craig Counsell #11 of the Chicago Cubs looks on against the Seattle Mariners at T-Mobile Park on August 23, 2026 in Seattle, Washington. (Photo by Steph Chambers/Getty Images)
Holmes will start the first game of Friday's doubleheader, while Peterson gets Game 2. That alignment could offer an important clue about Counsell's postseason plans.
Boyd appears firmly positioned for a Wild Card start after finishing the regular-season home schedule with seven innings of one-run baseball Thursday.
After that, Chicago has decisions.
Gausman's health could determine one of them. Peterson's performance could determine another.
The Cubs also have Shota Imanaga and several pitchers capable of working multiple innings out of the bullpen. MLB .com noted that Chicago could even leave some traditional starters off its Wild Card roster because a best-of-three series does not require a normal five-man rotation.
That makes Peterson's start in Boston more than another tune-up.
A few months ago, the Cubs acquired him because they desperately needed innings.
Now Peterson has a chance to make it difficult for Chicago to leave him out of one of the biggest games of the season.
This article was originally published on HEAVY
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