Cubs Pitching Matchups for Must-Win Series Against the Diamondbacks

The Chicago Cubs' back is suddenly against the wall.

After owning the top spot in the Wild Card race for the last couple of months, the Philadelphia Phillies have come flying in at full speed. Chicago's 19-2 win on Sunday at least kept their lead at 2.0 games, but that feels like nothing at this competitive point in the season!

Nevertheless, these next few days could go a long way toward locking in their spot. The Diamondbacks have underwhelmed all year, and Chicago is set to have some of their better arms on the mound. Let's go over the pitching probables for each game!

Game 1: Kevin Gausman (Cubs) vs. Merrill Kelly (Diamondbacks)

Aug 18, 2026; Chicago, Illinois, USA; Chicago Cubs pitcher Kevin Gausman (12) pitches against the Chicago White Sox during the first inning at Wrigley Field. Mandatory Credit: Patrick Gorski-Imagn Images | IMAGN IMAGES via Reuters Connect

Kevin Gausman will make his third start for the Chicago Cubs to open up the series in Arizona. The veteran is coming off a strange outing against the White Sox that ended with him being pulled from the game early with a hand cramp. He lasted just 4.1 innings, giving up 3 earned runs during that stretch with 5 strikeouts.

The flashes have already been there for Gausman, whose splitter can cause the kind of swings and misses that this rotation has lacked. At the same time, he's continued to drop some balls in the zone that have been hit hard. So far, he's given up a home run in each of his outings. Can he avoid that on Monday night?

As for Merrill Kelly, he hasn't been the same quality starter this season. He holds an 8-11 record with a 5.37 ERA. His WHIP has shot up to 1.52, as his off-speed stuff simply hasn't been freezing hitters nearly as often.

The walk rate, in particular, was always a strong mark for Kelly. But this now sits at just 10.1 percent, as he has at least four walked batters in three of his last four games. That's good news for a Cubs team that draws as many walks as anyone in the Bigs. As long as the Cubs' offense doesn't sputter, this should be a game where they make some noise. Kelly has handed over 6 runs in each of his last two starts.

Game 2: Clay Holmes (Cubs) vs. Brandon Pfaadt (Diamondbacks)

Aug 19, 2026; Chicago, Illinois, USA; Chicago Cubs pitcher Clay Holmes (25) pitches against the Chicago White Sox during the first inning at Wrigley Field. Mandatory Credit: Patrick Gorski-Imagn Images | IMAGN IMAGES via Reuters Connect

Clay Holmes is settling in just fine. The Cubs' marquee trade deadline acquisition has gone over 5.0 innings in each of his last two starts, holding his opponents to a combined 1 earned run. He's also only two starts removed from allowing only a single hit in 6.2 innings against the Cardinals.

As fans know, Holmes is all about forcing balls into the dirt. His ground ball rate is among the highest in the league at 59.6 percent. Thanks to his sinker, sweeper, and change-up, opponents are repeatedly missing the sweet spot on their bats and sending balls rolling toward the Cubs' elite defense. The Arizona offense has left a lot to be desired and is already known to make some iffy contact, so Holmes could be in for another solid evening.

Unlike Merrill Kelly, Brandon Pfaadt is having a career year. He's 7-1 and posting a 3.39 ERA over 98.1 innings of action. His bag is deep, and he mixes up his pitches extremely well. The Cubs' goal will be to lay off his curveball and sweeper in hopes of making contact with his change-up or fastball. For what it's worth, his change-up has been hit very well this year. Lefties can expect to see that pitch the most.

Game 3: Matthew Boyd (Cubs) vs. Eduardo Rodriguez (Diamondbacks)

Aug 21, 2026; Seattle, Washington, USA; Chicago Cubs starting pitcher Matthew Boyd (16) during the sixth inning against the Seattle Mariners at T-Mobile Park. Mandatory Credit: Steven Bisig-Imagn Images | IMAGN IMAGES via Reuters Connect

After several weeks of elite play, Matthew Boyd has come back down to earth. He's now given up 4+ runs in each of his last two outings, and he hasn't struck out more than three batters since the end of July.

Boyd hasn't necessarily looked horrible on the mound, but he is giving up far too many long balls, and the command hasn't been what Cubs fans are used to. With that said, Craig Counsell has still been giving him a pretty long leash to help save his bullpen. But will that continue if he has another rough first few innings? He wasn't afraid to pull Shota Imanaga early in Seattle!

This is especially true when we consider that the Cubs' offense is likely to have a tough day. Eduardo Rodriguez has been awesome all year. He has a 2.61 ERA in 26 games, which currently ranks 8th-best in baseball. To be clear, Rodriguez isn't making batters look silly with his velo or swing-and-miss stuff. He's simply been awesome at limiting hard contact and keeping balls in the park.

If Boyd can return to his July-self, we could be in for quite the pitchers' duel!

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