HOUSTON — The velocity on his pitches was down a few ticks. The stuff and the crispness just didn’t seem to be consistently there from start to start. And, well, Diego Castillo just didn’t feel right on the mound in his past few outings.

Instead of hoping that it might improve in the next few days, the Mariners decided to place Castillo on the 10-day injured list with right shoulder inflammation before Saturday’s game vs. the Astros. Right-hander Robert Dugger was recalled from Class AAA Tacoma and joined the team in Houston.

“Diego hasn’t been quite right the last couple times out,” manager Scott Servais said. “You’ve seen the back up a little bit in the velocity, and just the crispness to his pitches. … To his credit, he’s been trying to work through it. But coming out of his last outing, he didn’t feel great.”

Castillo was scheduled to meet with doctors Saturday afternoon in Houston to undergo testing on the shoulder, including an MRI to see whether there is any structural damage.

The big right-hander was acquired July 29 — a day before the MLB trade deadline — from the Tampa Rays in exchange for right-hander J.T. Chargois and infield prospect Austin Shenton. Castillo had served as one of the Rays best late-inning relievers, including the majority of their save opportunities

Before the trade, he had made 37 appearances for Tampa, posting a 2-4 record with 2.72 ERA with 14 saves. In 36 1/3 innings, he struck out 49 batters while issuing 10 walks and allowing five homers.


In 10 outings, since joining the Mariners he’s 0-1 with a 3.86 ERA and a save. In 9 1/3 innings pitched, he’s struck out eight batters, walked five and issued two homers.

The two homers allowed were memorable and came in separate series at Globe Life Field in Arlington, Texas. In his second outing with Seattle, he gave up a walk-off two-run homer to Jonah Heim.

And in his most recent outing, he served up a three-run homer to Jason Martin in a ninth-inning meltdown that sent the game to extra innings.

Castillo also had a blown save in New York. But he’d also delivered five scoreless outings for the Mariners and only allowed three total hits in his nine outings.

In his two outings during the series vs. the Rangers, Castillo’s sinker averaged around 92 mph, which is down about 2 mph while his slider was down about 1 mph. The spin rate on both pitches was down slightly, and he had trouble commanding both pitches at times. These aren’t alarming decreases, but they pose enough concern that a stint on the injured list isn’t a bad option to see whether it can return.

Dugger’s stay with the team might be short-lived. He pitched in Saturday’s drubbing, giving up six runs on seven hits in 3 1/3 innings relief of starter Logan Gilbert.


The Mariners will likely option Dugger back to Tacoma after the game and bring in a fresh arm for the Sunday’s series finale and the two-game series in Oakland.

Sheffield has stronger rehab start

Left-hander Justus Sheffield (left forearm/oblique strain) made his second rehab start Friday night for Class AAA Tacoma and looked much more comfortable compared to his first rehab start.

Sheffield pitched four innings, allowing two runs on three hits with no walks and seven strikeouts. It’s a considerable improvement from his previous outing of 1 1/3 innings, four runs allowed on two hits with five walks and two strikeouts.

From the blog of Rainiers’ radio announcer Mike Curto: “The first two batters Sheffield faced hit a single and then a homer. After that, Sheffield retired 12 of the next 13 hitters, striking out seven with no walks.

“Most important, Sheffield repeatedly got ahead in the count. His control was much improved over his first rehabilitation start last weekend at Cheney Stadium, when he looked like a guy who hadn’t pitched in six weeks.”

Sheffield could make another start with Tacoma to push his pitch count up to 80 pitches. Or the Mariners might recall him from the Rainiers for the upcoming homestand and use him as a long reliever in the bullpen with five healthy starters in the rotation.