The Cubs had time before the start of the playoffs to make a decision about rookie right-hander Cade Horton.
But they learned what they needed to after Horton threw on the outfield grass Saturday at Wrigley Field.
‘‘He went out and threw today, and it was just a ‘no,’ ’’ Cubs president Jed Hoyer said. ‘‘He was in discomfort, felt like he couldn’t really let it go and pitch the way he needed to and throw the way he needed to. We had to shut that down.’’
The Cubs put Horton on the 15-day injured list with a fractured rib, rendering him unavailable for the entirety of their best-of-three National League wild-card series against the Padres that begins Tuesday.
The move is retroactive to Thursday, meaning the earliest Horton would be able to pitch in the postseason would be a potential Game 5 of the NL Division Series on Oct. 11. That’s if the Cubs make it that far, if he’s healthy by then and if an injury forces another player off the playoff roster.
In other words, the Cubs might be without their best pitcher for the first two rounds of the playoffs.
‘‘He really wanted to pitch, felt like he could do it,’’ Hoyer said. ‘‘I don’t know what that means for deep October. . . . But, obviously, he’s going to be out for the foreseeable future.’’
It’s a potentially critical blow to the Cubs’ postseason fortunes, given that Horton has been dominant since the All-Star break. He has been one of the best pitchers in the majors since the break with a 1.03 ERA in his last dozen starts.
But his most recent start ended when he was pulled after three innings Tuesday against the Mets. That came after Horton was sick during the Cubs’ series last weekend in Cincinnati. After opting to test Horton in that start, the Cubs got a diagnosis of the fractured rib Wednesday.
‘‘The honest answer [is], I don’t think we know [exactly what caused the fracture],’’ Hoyer said. ‘‘He was sick in Cincinnati. And with that, there was coughing. Whether that did it or not, we don’t know. There was no acute event that we know of. Just his ribs were sore, and it got worse.
‘‘Had we not pitched him [Tuesday], the next time he would have pitched would have been, in theory, [in a playoff game], and I think we would have found out pretty quickly that it wouldn’t [have worked]. . . . Ultimately, it’s not a decision we regret. We had to find out.’’
The Cubs now must chart a path forward without their hottest pitcher, seeing whether they can survive potentially two series without Horton’s help.
Top-of-the-rotation left-handers Shota Imanaga and Matthew Boyd will be rested for Games 1 and 2 against the Padres, but both have struggled. After yielding eight runs Thursday to the Mets, Imanaga has a 5.97 ERA in his last six starts. Boyd has an even uglier 6.08 ERA in his last seven starts.
Right-handers Colin Rea and Jameson Taillon have been more successful of late, with a 2.63 ERA and a 1.54 ERA, respectively, in September.
With Horton’s status a question, the Cubs intentionally shifted Taillon’s start from Sunday to Saturday to assure he would be rested for a potential Game 3 against the Padres. After the game, manager Craig Counsell said Taillon is going to ‘‘play a part’’ in the team’s planning.
Counsell, who has spent the season preferring to call his pitchers ‘‘out-getters’’ rather than assigning specific titles, is amping up that approach heading into the playoffs.
With the way teams use pitchers so differently in October, it’s reasonable to expect any and every combination of hurlers.
‘‘I don’t think there are any roles,’’ Counsell said before the Cubs put Horton on the IL. ‘‘Those two words, [starter and reliever], go out the window. Those words are irrelevant. I’m using the word ‘out-getters’ because that’s really what happens at this time of year.
‘‘How do we get 27 outs? That’s all that matters. . . . Everything is on the table.’’