How optioning Caleb Kilian affects the Cubs’ rotation

PITTSBURGH — The Cubs optioned top pitching prospect Caleb Kilian to Triple-A Iowa on Tuesday after consecutive rough starts. But more went into the decision than a couple of box scores.

“It’s twofold,” manager David Ross said before the Cubs’ 7-1 loss to the Pirates. “We need protection, and Caleb has a few things we need him to work on and come back and be a better version of himself. We’ve seen some flashes but just get him back on track a little bit.”

Injuries to the big-league staff pushed both of Kilian’s call-ups ahead of schedule. And he has been working to make his delivery more consistent.

“There’s a lot going on in my head, a lot I’m working on,” Kilian said after allowing five earned runs in 2⅓ innings Monday against the Pirates. “So maybe that’s part of it.’’

Ross said: “Working on things at this level and putting the pressure on yourself isn’t always the easiest spot to do it.”

As for the “protection” Ross referenced, since MLB implemented the twice-delayed 13-pitcher roster limit, the Cubs have one fewer pitcher to help them weather short starts.

It’s too early to say who will take Kilian’s next turn, Ross said.

The Cubs have options. They recalled right-hander Mark Leiter Jr. from Triple-A as the corresponding move. He held the Pirates to one run through three innings. But Alec Mills threw 4⅓ innings Monday, so unless the Cubs use him for length out of the bullpen in the next few days, he’d be on schedule to replace Kilian.

The Cubs have three starters on the 15-day injured list. Left-hander Wade Miley (strained left shoulder) hasn’t started throwing yet. But lefty Drew Smyly (right oblique) threw a bullpen session Tuesday, and right-hander Marcus Stroman (strained right shoulder) is scheduled to throw his first bullpen session Wednesday since landing on the IL.