By Bruce Levine–

CHICAGO (CBS) — Despite a hitting slump that has seemingly lasted all season for the defending champion Cubs, pitching is the main focus for the front office.

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A 5-3 loss to the Rockies on Friday afternoon at Wrigley Field has dropped the Cubs back to .500 at 30-30 and once again reflected their shortcoming. The hitting struggles have been exacerbated by a National League-worst .217 batting average with runners in scoring position, but it’s still the starting pitching depth that is top of mind.

Friday reminded of that, with right-hander Kyle Hendricks missing his start with inflammation in his right hand. Left-hander Mike Montgomery, used mostly as a long man this year, slid into the starter’s role. He did fine in taking a no-decision in four innings, allowing just a two-run homer to Ryan Hannigan, but it wasn’t enough as the Rockies took control with two runs in the fifth inning off reliever Seth Frankoff, who was making his big league debut.

Montgomery competed with left-hander Brett Anderson for the No. 5 starter role out of spring training but was deemed essential out of the bullpen. Anderson has since gone to the disabled list and right-hander Eddie Butler joined the rotation. When Montgomery starts, it changes the bullpen equation and hurts the left-handed depth among relievers for manager Joe Maddon, who turns to Brian Duensing as his only southpaw then.

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Montgomery may stay in the rotation as a sixth starter once he’s stretched out and Hendricks returns. Hendricks is expected to be ready to go next weekend.

“The mentality you have to have is to go out there no matter what the role is and make good pitches,” Montgomery said. “No matter what that job is, you must have the same mentality.”

The Cubs’ signing of Anderson in the offseason and trades for Montgomery and Butler in the past year were decisions made with depth in mind after the rotation has been nearly injury-free the past two season. But now this group isn’t anything near 2016’s dominant starting rotation, which led all of baseball in ERA. Cubs starters had a 4.65 ERA entering play Friday, 21st in MLB, and they’re not going as deep into games.

Executives Theo Epstein and Jed Hoyer are well aware of this. It’s why the Cubs have numerous scouts looking at certain pitchers for possible trade scenarios.

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Bruce Levine covers the Cubs and White Sox for 670 The Score and Follow him on Twitter @MLBBruceLevine.