CHICAGO -- As the Wrigley Field organ played and the crowd hummed on Friday afternoon, Cubs starter Marcus Stroman held court with reporters down a hall from the press box. The reality he is grappling with is that there is no clear timeline for his return to the mound Jameson Taillon was on at that moment.

The Cubs are facing a six-week push for a potential postseason berth and Stroman is facing a comeback from a fracture in the cartilage in his right rib cage. During a 4-3 loss to the Royals, Stroman expressed optimism that the North Siders could complete the journey to October, even if he is not part of the picture.

¡°We¡¯re right in the thick of it,¡± Stroman said. ¡°You see how we¡¯re playing. I truly believe we can win the division and once you¡¯re in the playoffs, it¡¯s anyone¡¯s game. No one¡¯s a bigger believer in the Cubs than me.¡±

The Cubs have been operating without Stroman -- while chipping away at the deficits in the National League Central and Wild Card races -- for nearly three weeks. He initially landed on the injured list with a hip issue after his last outing on July 31. The setback with his rib cage was a recent development.

Sans Stroman, Chicago¡¯s rotation is headed by All-Star Justin Steele and a pair of veterans in Taillon and Kyle Hendricks. Javier Assad¡¯s recent run of success has earned him a spot on the staff, while lefty Drew Smyly and righty Hayden Wesneski offer options for the fifth spot.

Taillon, specifically, knows how important he will be down the stretch.

¡°It¡¯s no secret Stro was one of the best pitchers in baseball for like two months,¡± Taillon said. ¡°We would love to get him back. I really have no clue what his timeline is or where he¡¯s going to be at, but it¡¯s a good opportunity for me. ¡­ I have an opportunity in front of me to step up and prove why they went and got me.¡±

Taillon, who signed to a four-year, $68 million contract in free agency last offseason, logged a quality start against Kansas City. A few miscues behind him led to two of the four runs on his six-inning line going in the book as unearned. It was a solid performance on a day Chicago¡¯s lineup went relatively quiet.

¡°I thought he threw the ball pretty well,¡± Cubs manager David Ross said. ¡°Overall, I thought it was a good outing.¡±

Taillon has turned in a 3.69 ERA over his last eight starts, following a 14-start stretch to open his campaign that included a 6.93 ERA. The big right-hander¡¯s turnaround happened around the same time Stroman¡¯s season went south. An All-Star with a 2.28 ERA in his first 16 turns, Stroman had a 9.00 ERA in seven outings prior to landing on the IL.

The Cubs and Stroman fully expected him to be back for a start on Wednesday, but things changed in a hurry.

After throwing a light bullpen session on Sunday in Toronto, Stroman fielded some ground balls on the infield (something he does routinely) and then headed inside. According to the pitcher, it was after he cooled down in the clubhouse that an earlier ¡°crampy¡± feeling developed into his having trouble breathing.

¡°It was pretty alarming, pretty scary,¡± Stroman said.

Stroman was cleared to travel home with the team and headed to an ER in Chicago, where they did tests to rule out appendicitis or an issue with his gallbladder. Once those possibilities were eliminated, he underwent an MRI exam on Monday¡¯s team off-day and learned of the fractured cartilage.

¡°I¡¯m still trying to process it,¡± said Stroman, who added that he has no idea how this particular injury happened. ¡°I can barely turn right now. Breathing at some points, to sit for long periods of time, is pretty difficult. So, I¡¯m just kind of taking it day by day.¡±

Stroman said he will need an undetermined period of rest before he can build a rehab schedule. The pitcher was not sure if that meant this was the end of his season, which echoed what president of baseball operations Jed Hoyer said earlier this week.

¡°We don¡¯t really know yet,¡± Hoyer said. ¡®It¡¯s an unusual injury for a pitcher, so we¡¯re going to kind of wait and see. Obviously, it¡¯s going to be a real rest time, but unclear about what that means at that point.¡±

All the Cubs really know for certain is that their depth will be tested as the team continues its quest for playoff baseball.

¡°I don¡¯t want to take away from everything we have going on right now,¡± Stroman said. ¡°Hopefully I can get it right and then come back, hopefully, at some point and we¡¯re in a playoff push. And hopefully I can contribute.¡±