With Kyle Hendricks’ return from injury appearing imminent, the Chicago Cubs will need to reshuffle their starting rotation to make room for the 27 year old right-handed pitcher who has been on the disabled list since June 5 with tendinitis in the middle finger of his right hand.

Which Cubs pitcher becomes the odd man out once Hendricks returns is anybody’s guess at this point. Since June 5, the Cubs have employed Jon Lester, Jake Arrieta, and John Lackey, stayed with typical fifth starter Eddie Butler, and moved long reliever Mike Montgomery from the bullpen to the starting rotation.

Unless the Cubs utilize a six-man rotation once Hendricks returns (which is unlikely since they’re in the thick of an intense playoff race and can’t afford to rest starters), the team will face a difficult decision regarding the makeup of the starting rotation moving forward. What can they do?

Status Quo

The most likely (and boring) scenario is the Cubs return to the pre-injury starting rotation status quo.

Hendricks slips back into the starting rotation with Lester, Arrieta, Lackey, and Butler and Montgomery returns to his long-relief duties.

However, this structure is problematic because it wasn’t successful when the Cubs utilized it earlier in the season. From May 12 (when Butler made his first start of the season) until June 4 (the day before Hendricks’ injury), this starting rotation posted a 4.78 ERA which was 19th-best in MLB. In contrast, from June 5 until today the Cubs starting rotation has posted a 3.66 ERA which is third-best in MLB in that time frame.

The difference? Well, Arrieta and Lackey have had some better starts in the second time frame, but the most substantive difference maker has been Montgomery. In three games, the lefty has posted a 2.40 ERA while keeping his walks under control (six total) and limiting opponents to a .218 batting average against.

Granted, this is a super small sample size, but his early success as a starter which has helped buoy a previously struggling rotation makes it dangerously simplistic for the Cubs to just return to the status quo.

Montgomery; Butler Switch Roles

Once Hendricks returns, perhaps keeping Montgomery in the rotation and moving Butler to a long-relief spot would optimize the talents of both players.

As previously stated, Montgomery has sparkled in his three starts this season, and sports a large arsenal of effective pitches that gives him more of the profile of a starter rather than a reliever. The biggest issue for Montgomery is pitching deep into games, as he pitched through four, five, and six innings in his three games as a starter this season. Walk rate is a major factor at play here, as he has averaged a career-high 4.5 base on balls per nine inning rate (bb/9) this season. However as a starter this year, he has harnessed that number in a bit, averaging just 3.6 bb/9.

However, all of Montgomery’s major pitfalls as a pitcher are magnified when applied to Butler. In eight starts, Butler has pitched until at least the sixth inning only once while his bb/9 rate sits at 4.9. He is also surrendering heavy traffic on the base paths as evidenced by his 1.422 WHIP this season which has further contributed to his struggles pitching deep into games.

Furthermore, Butler’s arsenal of pitches is less extensive than Montgomery. The former relies mostly on two fastballs (a sinker and a four-seam fastball) and a curveball which comprise approximately 85 percent of the total pitches he throws. In contrast, Montgomery has five pitches that he throws at least 10 percent of the time.

Montgomery’s pitching arsenal screams starter while Butler’s high-velocity fastball (both his fastballs average about 93.5 mph and his four-seam fastball peaks in the mid-90s)and less extensive repertoire of pitches may be best suited for the bullpen. Butler has had difficulty pitching deep into games and his stats fall off a cliff the more times a hitter sees his stuff.

Executing a quick role switch for Butler and Montgomery maximizes both players’ talents and may be the way the Cubs want to go moving forward.

Get Lackey Out of There!

This seems like the most unlikely of the three scenarios, but maybe the Cubs explore the option if Lackey continues to struggle.

In his age-38 season, Lackey has endured a sharp dip in his pitching production. He’s posted a 4.74 ERA through 15 starts which is 28th in the National League out of 40 qualified starters. Right now, he isn’t the pitcher the Cubs want manning the mound during a heated playoff race let alone a pitcher who can throw competently in the playoffs.

The Cubs won’t do it, but removing Lackey from the starting rotation in favor of Montgomery while keeping Butler in the fifth spot could benefit all parties involved except Lackey’s ego.

The Cubs face another important decision as they continue the process of figuring out how to maximize their rotation once Kyle Hendricks returns from injury. The previous setup underwhelmed expectations, and it’s time for the Cubs to try shaking things up in the starting rotation in hopes that they stumble upon a setup that works long term.