The Twins announced Wednesday that they’ve designated right-hander Diego Castillo for assignment. His spot on the 40-man roster will go to righty Jay Jackson, whose contract is being selected from Triple-A St. Paul. Right-hander Louie Varland was optioned to St. Paul to open an active roster spot for Jackson, who’ll be up for his second stint of the year in Minnesota.
Castillo inked a minor league deal during spring training and was selected to the MLB roster late last month. He’s only allowed two runs in seven innings of relief but has also issued an unsightly seven walks in that span.
The veteran Castillo has pitched quite well in Triple-A, logging a 2.50 ERA with a 29.7 percent strikeout rate, 8.1 percent walk rate and 54.5 percent ground-ball rate in 18 innings. He also saw his average fastball velocity jump back to 95.7 mph after sitting at 94.2 mph in 2023. The Twins will have a week to trade Castillo, attempt to pass him through outright waivers or release him.
From 2018-22, the now-30-year-old Castillo was excellent out of the bullpens in Tampa Bay and Seattle, pitching to a combined 3.12 earned run average (3.69 FIP, 3.38 SIERA) with a strong 28.1percent strikeout rate and an 8.9 percent walk rate that’s barely north of the league average. He kept the ball on the ground at an impressive 50.7 percent clip as well, and Castillo yielded just 1.07 long balls per nine frames.
A series of three shoulder injuries looked to have taken their toll on him, as last year’s 94.2 mph average fastball was a career-low and he was rocked for six runs in 8 2/3 innings with Seattle (while walking 17 percent of his hitters and plunking another one).
It’s feasible that his track record and this year’s rejuvenated fastball could lead to interest from a bullpen-needy club, be it via a minor trade or a waiver claim.
Jackson, 36, signed a one-year, $1.5M deal with the Twins over the winter but was hit hard in his initial stint with the club. In 22 1/3 innings, he pitched to a 6.85 ERA, yielding runs in 10 of his 17 appearances along the way.
He’s allowed one run in three Triple-A innings since being designated for assignment, clearing waivers and being sent outright to St. Paul. Jackson worked mostly in low-leverage spots with the Twins and figures to do so again, unless he can more closely resemble the 2022-23 version of himself — wherein he combined for 31 innings of 2.03 ERA ball.
Because of his contract, this could become a frequent cycle for Jackson. His remaining salary makes it unlikely he’ll be claimed on waivers, so the Twins could designate him, pass him through waivers, outright him and then re-select him to the big league roster multiple times this year — whenever the need for a fresh arm arises.
Of course, if Jackson can indeed begin to recapture some of his form from recent seasons, he could also pitch his way into a more permanent role in manager Rocco Baldelli’s bullpen.
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