3 Things Mariners Fans Should Expect From Kade Anderson’s MLB Debut vs. Cubs

Seattle’s future takes the mound with the present watching closely.

Jul 12, 2026; Philadelphia, PA, USA; American League pitcher Kade Anderson (32) throws a pitch against National League in the first inning at Citizens Bank Park. Mandatory Credit: Kyle Ross-Imagn Images | IMAGN IMAGES via Reuters Connect

The Mariners have given us plenty of reasons to keep one eye on what’s going on in Arkansas this season. Some will be closing the tab on Aug. 22 when Kade Anderson takes the mound for his first career MLB start at T-Mobile Park.

The 22-year-old lefty will make his debut against the Chicago Cubs, bringing one of baseball’s most electric prospect résumés with him. That brings pressure, especially against a lineup that won’t be easy to navigate. Here’s what we should expect when Anderson takes the ball.

Kade Anderson’s Fastball Velocity Won’t Tell the Whole Story in His Mariners Debut

We have become spoiled by pitching prospects who open the conversation at 98 mph. Anderson is a different kind of animal. His four-seam fastball generally sits between 92 and 94 mph, though he can reach back for 97. Don’t be surprised if he comes out a little hot with adrenaline. But expect the velocity to settle down.

He understands how his stuff is supposed to move. More importantly, he knows where to put it.

The changeup is the pitch Mariners fans should circle. It arrives in the mid-80s with late fade and sink, giving right-handed hitters a miserable decision after they have geared up for the fastball. Anderson can also spin a high-80s slider and a slower curveball with sharp vertical break.

If he stays ahead in the count, we should see why minor league hitters spent the season walking back to the dugout.

The Cubs Will Make Anderson Earn Everything

There were easier places to schedule a major league debut. Instead, he’ll be getting his debut against a team that has spent the season playing like a legitimate contender, with enough power, patience and lineup depth to ruin a young pitcher’s afternoon. The Cubs are pesky and can force pitchers to work. Anderson does have one immediate advantage: nobody in Chicago’s lineup has faced him in a major league game.

That unfamiliarity should help the first time through the order. The advantage starts shrinking once the lineup turns over. Major league hitters adjust fast. Don’t be surprised if they begin recognizing how he wants to finish at-bats and which pitches he trusts when behind in the count. The opening innings will be important. The Cubs only have three lefty bats on their roster, so Anderson may need to tread lightly here.

Expect a Short Leash and a Few Messy Moments

We should probably clear one unreasonable expectation off the table: Anderson doesn’t need to throw seven shutout innings to justify the hype. He’s making his first major league start after jumping directly from Double-A. There will be nerves. His fastball command will probably run a little hot during the first inning. This is all normal stuff. 

The Mariners will also have his workload in mind. Anderson has already thrown 93 1/3 professional innings after working 119 innings for LSU in 2025. The organization isn’t going to abandon that care and squeeze every possible pitch out of him during his first afternoon at T-Mobile Park.

Four or five competitive innings would be a perfectly useful debut. The real evaluation should center on how Anderson responds when something goes wrong. That answer will tell us more than the final line.