The Chicago Cubs’ pitching rotation took a brutal hit on Saturday.

The team announced they’re putting their star rookie pitcher on the injured list, which will keep him out of next week’s NL Wild Card round.

What we know:

The Cubs have placed pitcher Cade Horton on the injured list, retroactive to Sept. 25, with a right rib fracture.

This will keep one of baseball’s top pitchers in the second half, who is also a leading NL Rookie of the Year, candidate from at least the first round of the playoffs.

Horton was removed after the third inning from his last outing on Sept. 23 with back tightness. Counsell said after that a recent illness included a persistent cough led to the back tightness, as Horton had some issues taking deep breaths.

So far this season, the 24-year-old rookie pitcher has recorded a 2.67 ERA on 118 innings pitched. Since the All-Star break, Horton has a league-leading 1.03 ERA with seven earned runs through 61.1 innings pitched.

In a corresponding move, the Cubs have recalled pitcher Jordan Wicks. 

What’s next:

At the earliest, Horton will be eligible for reinstatement at Oct. 10. This means he’ll be available for Game 2 of the NL Divisional Series, if the Cubs make it that far.

It’s an unexepected development, and a frustrating one, for a pitcher who could be the NL Rookie of the Year. Those unexpected-yet-frustrating developments have been too common for the Cubs this season.