AquaSox pitcher Williamson promoted to Double-A Arkansas

Everett AquaSox pitcher Brandon Williamson has been promoted to Double-A Arkansas, according to the Seattle Mariners’ player development Twitter account.

The 2019 second-round draft pick has a 3.19 earned-run average in 31 innings pitched this season, over the course of six starts with the AquaSox.

Williamson has been a strikeout machine, with 59 punchouts and just 10 walks. The 6-foot-6 left-hander has struck out 1.9 batters per inning and 47.6% of the batters he’s faced — both of which are the best marks by a wide margin among qualified pitchers in the six-team High-A West.

Williamson, ranked by MLB.com as the No. 9 prospect in the Mariners’ organization, has a 1.00 WHIP (walks plus hits per innings pitched) and a .189 opponents’ batting average.

The Minnesota native allowed five runs in one start this season and four in another. Over his other four starts, he yielded just two runs combined.

Williamson’s best outing came on May 29 against the Vancouver Canadians, when he allowed just one run and two hits in 7 1/3 innings. He struck out 13 of the 25 batters he faced in that game.

After being drafted by the Mariners out of Texas Christian University, Williamson made 10 appearances with the AquaSox in 2019, back when Everett was a Short Season-A club. He posted a 2.35 ERA in 15 1/3 innings that season, with 25 strikeouts and just five walks.