Diamondbacks promote 2019 first-round pick for MLB debut

The Diamondbacks announced that they have optioned left-hander Andrew Saalfrank, with fellow lefty Blake Walston recalled in a corresponding move. The latter will be making his major league debut as soon as he gets into a game.

Walston, 23 next month, was the club’s first round pick in 2019. The Diamondbacks used the 26th overall pick of that year’s draft to grab Walston out of New Hanover High School in Wilmington, North Carolina.

He got a brief debut in the professional ranks in 2019, but then the minors were canceled due to the pandemic in 2020. He tossed 95 2/3 innings in 2021 between Single-A and High-A with a 3.76 earned run average, 28.8% strikeout rate and 8.1% walk rate.

In 2022, he returned to High-A but cruised through four starts before getting bumped up. He had a 5.16 ERA over his 21 Double-A starts that year, despite decent peripherals. He struck out 24% of batters faced and walked 8.5%, but a .341 batting average on balls in play and 14.5% home run per flyball rate added some extra runs.

Last year, he was sent to Triple-A and had a 4.52 ERA over 30 starts. He walked 14% of batters faced while only striking out 15.6% of them. He was added to Arizona’s 40-man roster in November to keep him out of the Rule 5 draft and returned to Triple-A this year. Through 20 2/3 innings this season, he has walked 15.3% of batters faced, striking out 19.4%, leading to a 4.79 ERA. Were it not for a 77.6% strand rate, he may have fared worse, which is why his FIP is at 6.36.

That lack of control perhaps points to a future relief role but he is still quite young and has time to rein in his stuff. The Diamondbacks have continued to stretch him out, suggesting they still believe in his potential to stick in a rotation at some point. 

Baseball America ranked him the No. 11 prospect in the club’s system coming into this year.

For now, he’s likely on the roster to give the club a multi-inning option out of the bullpen due to some strange circumstances. Jordan Montgomery was supposed to start Tuesday's  game before it was delayed by a colony of bees that had taken up residence in the netting behind home plate. The start of the contest was delayed by about two hours while was called who could remove the bees, and the club decided to scratch Montgomery in that time. 

It seems fair to assume that Montgomery had already gone through some pregame preparations and the club didn’t want to ramp him back up again after a lengthy shutdown, similar to how pitchers often don’t return after long rain delays.

In the end, the Snakes went with a bullpen game and used seven different pitchers to cover 10 innings, as they eventually defeated the Dodgers in extra innings. Montgomery is taking the ball Wednesday but with a weakened bullpen, so Walston may be tapped, especially if Montgomery is bounced early.