Mariners rival promoting highly-touted pitching prospect to face Seattle in MLB debut

One of the most exciting pitching prospects in the sport will get his first shot at the show on September 12, the first game of a four-game series between the Rangers and Mariners. After being taken in the first round (twice) and receiving Tommy John surgery in 2023, he pitched a total of just 64.2 innings of professional baseball to the tune of a 3.20 ERA and 0.88 WHIP. His start against Seattle will be just his 17th professional game.

Rocker spent his 2024 split between Double-A Frisco and Triple-A Round Rock, making a total of seven starts. Known for his exceptional stuff and raw talent, his arsenal mainly consists of a slider and four-seam fastball with an occasional sinker or changeup. His four-seam fastball sits at 98 mph with the ability to get up to 100 mph while his slider hovers in the mid-80s with 42 inches of vertical drop.

His sinker seems to be a developing pitch with it being added with his move to Triple-A, but the intrinsic properties already seem strong. It has a velocity in the high-90s similar to his four-seam fastball and 14.8 inches of arm-side break.

This move comes as the Rangers have all but been eliminated from the postseason and could provide a glimpse of what the Mariners' division rival could have to offer in their future rotation. With the Rangers' litany of injuries that have sidelined the likes of Jon Gray, Max Scherzer, and Tyler Mahle along with Jacob DeGrom who's still recovering from his second Tommy John, this gives a chance for their young arms like Rocker and Jack Leiter to get some big league experience without too much consequence to the Rangers' regular season.

The Mariners, on the other hand, need every win they can get. Their own playoff chances stand at just 7.4% according to FanGraphs and every loss is a devastating blow that sets them further off course. Many have likely given up hope already but Seattle isn't out of the fight just yet.

Because there's such a small sample size of Rocker's pitching, especially at the high levels of the minor leagues, it's hard to say whether he's as good as his 44.3% strikeout rate and 3.8% walk rate really make him out to be. He's never faced hitting at the caliber of a major league team and even if Seattle's lineup has been relatively anemic all year, they've started to show up in recent weeks. If they can keep up the momentum they started gathering in the second half of the Oakland series, they'll surely overcome the newest obstacle to their trip to October baseball.