Getting to know Mariners pitching prospect Brandon Williamson

The Mariners have a bit more depth in the minor league system than was originally expected heading into the 2021 season. Brandon Williamson qualifies as one of those players.

He was already ranked in the top 30 for the Mariners in their prospect rankings but has climbed all the way up to 9th in their team rankings, currently taking the spot as the top lefty pitcher in the organization.

The Mariners got a steal when they signed Brandon Williamson in the second round in 2019.

He is a massive lefty, already putting him in a fantastic position to succeed just from being a left-handed pitcher that is 6’6″. The Mariners took him for below value in 2019, even though there was a risk from his surgery on both hip labrums. He was actually the second-best lefty who was 6’6″ from TCU, as Nick Lodolo was taken 7th overall by the Reds.

He seems to have recovered just fine from that and has turned into a strikeout machine. No, I don’t mean that he is striking out a measly 12-13 guys per 9. He is striking out just under 18 per 9, having sat down 51 hitters in just 25.2 innings. That’s an insane rate. It comes from a mix of the mid-90’s fastball that rides and is harder to pick up from Williamson’s throwing motion. It’s paired with a deep curveball and a slider that will occasionally show up with a hard bite.

When you take a look at the repertoire, you can see that fastball and curve as his top two pitches, and they are doing enough so far to roll through A-Ball. He is working on the cutting slider, but also has a changeup as his fourth pitch. Having a strong and deep pitching coach staff in the Mariners system will help his development, and they already have him throwing the change-up more than he did in college.

The worry with someone who is striking out a ton of batters is their command. Are they someone who is only sitting hitters down because they are “effectively wild”? It doesn’t seem to be the case with him, as he has issued just 7 walks so far, keeping it at 2.5 per 9, which is a wonderful number this early in his career. He’s averaging just over five innings a game also, which is nice to see that the team is letting him stretch out and throw into the sixth inning.

The only downside to his season so far has been giving up the long ball. Four of his 18 hits allowed have been home runs, meaning that he gives up a homer on 22.2% of his hits allowed. Surely, that number will come down at some point, but it is worth keeping an eye on. Part of this could be from working on his 3rd and 4th pitches, but its hard to complain too much when 2 of 3 outs every inning are a strikeout.

Don’t expect Brandon Williamson to sit around in Everett for too long. Most scouts expect him to be on the big league squad in 2023. With a WHIP of 0.97, an opponent’s average of .196, and that incredible K rate, he deserves a chance to move up to Arkansas and see if he can continue to perform similarly against stronger competition. The Mariners have a great trio of righties with Kirby, Gilbert, and Hancock. Williamson is showing that he deserves to be included, especially as a lefty.