Mariners Underrated Prospect: Brandon Williamson

The Seattle Mariners have one of the best farm systems in all of baseball. They have several top prospects, and many young players who have recently graduated from prospect status such as Jarred Kelenic, Logan Gilbert, and Evan White. These players get lots of fanfare and are well known by Mariners fans, but there are some players who are not as well known. One of these such players is Brandon Williamson.

Brandon Williamson is a tall, lanky, left-handed starting pitcher, who was drafted in 2019 out of Texas Christian University. Standing at 6’6″ and weighing about 210 lbs., Williamson is a prototypical tall lefty pitcher; he has a big leg kick and a fluid movement to the plate, that isn’t close to max effort, and is easily repeatable. With his good extension, the ball gets up on hitters faster due to Williamson’s size.

Williamson has a good 4-pitch mix, featuring a fastball in the mid 90s. His best off-speed pitch is his curveball, which he uses as an out pitch, especially to lefties. He also has a slider that is still developing, as well as a changeup that he is working on more in the minor leagues than in college. He could have four useful pitches in his arsenal, making him a very effective starting pitcher.

Williamson started the year at High-A Everett, and was dominating hitters with his fastball. In six starts at Everett, Williamson struck out 59 batters, posting 17.1 strikeouts per nine innings, and hitters could not catch up to his mid to upper 90s fastball. When he got promoted to Double-A Arkansas in June, he did not stop striking dudes out; he struck out 94 in 13 starts for a 12.6 K/9.

In his first inning at AA, Brandon Williamson threw an immaculate inning:

Williamson, 23, will probably start next year in AA or maybe in Triple-A Tacoma, and is one of the Mariners’ starting pitching prospects that could reach the big leagues. If his four pitches develop the way they are currently trending, he should contend to be a good middle of the rotation pitcher in a future rotation.

A player comparison for Williamson, that Mariners fans should like, is James Paxton. Both are tall lefties, with their best pitches being their fastballs and curveballs. Under Seattle’s excellent current player development system, the Mariners should hope that Williamson can stay healthier than Paxton, and be able to contribute more long-term value.

The Mariners have a plethora of pitching talent, and one of the most overlooked players is Brandon Williamson, who has all the physical stature, stuff, and command to be a solid mid-rotation starting pitcher for years to come in Seattle.