Castillo (shoulder) was activated off the injured list Saturday.

EDGE Analysis

Castillo wound up missing two weeks with right shoulder inflammation. He's only recorded one save in 10 appearances for the Mariners since coming over from the Rays at the deadline, but he should be one of the team's top ninth-inning options down the stretch. Paul Sewald has saved eight games this season while striking out 41.0 percent of opposing batters en route to a 2.44 ERA, however, so Castillo could face stiff competition for save chances.

The Mariners plan on sending Castillo (shoulder) to their rookie-level Arizona Complex League affiliate for a one-game rehab assignment before activating him from the 10-day injured list Saturday or Sunday, Corey Brock of The Athletic reports.

EDGE Analysis

Because the Mariners are playing a three-game set in Arizona this weekend, the organization wants to keep Castillo nearby for his rehab assignment rather than having him report to a higher-level affiliate. Castillo has been sidelined for only a week and a half with the inflamed right shoulder, so one tune-up outing in the minors should be all he needs to prove to the Mariners that he's healthy. Once reinstated from the IL, Castillo should re-emerge as a factor in Seattle's closer picture.

Castillo (shoulder) felt good after throwing a bullpen session Monday, though he's expected to need a rehab outing before returning from the injured list, Daniel Kramer of MLB.com reports.

EDGE Analysis

The Mariners previously expressed optimism that Castillo could return after spending the minimum 10 days on the injured list, but that won't be happening, as that window expired Monday. It doesn't look as though he'll miss too much more time, but he'll miss at least a few more days if the Mariners do indeed go ahead with the rehab assignment.

The MRI that Castillo underwent Saturday revealed nothing more than fatigue in his inflamed right shoulder, Shannon Drayer of 710 ESPN Seattle reports.

EDGE Analysis

Since Castillo isn't dealing with any structural damage to his shoulder, the Mariners are optimistic that he'll be ready to return from the 10-day injured list when first eligible Aug. 30, or soon after. Until then, the Mariners are likely to turn to Drew Steckenrider and Paul Sewald as their primary options in save scenarios.

Castillo (shoulder) will undergo an MRI to determine the severity of his injury, Shannon Drayer of 710 ESPN Seattle reports.

EDGE Analysis

Castillo landed on the 10-day injured list with right shoulder inflammation Saturday, and his MRI will help determine whether he's dealing with any structural issues. The Mariners aren't yet sure when the right-hander will be able to return to action.

Castillo was placed on the 10-day injured list with right shoulder inflammation Saturday, retroactive to Aug. 20.

EDGE Analysis

Castillo was charged with a blown save Thursday when he allowed two runs on a hit and a walk while striking out two in one inning, and his injury helps provide an explanation for his struggles. It's not yet clear whether the right-hander will miss more than the minimum of 10 days, but Paul Sewald will likely see increased save chances in Castillo's absence.

Castillo was charged with his fifth blown save of the season in an extra-innings win over the Rangers on Thursday, allowing two earned runs on a hit, a walk and a wild pitch over one inning. He struck out two.

EDGE Analysis

Castillo inherited a two-on, none-out situation when he entered the game in the bottom of the ninth, and he ended up hurting his own cause by uncorking a wild pitch and allowing a game-tying three-run home run to Jason Martin. The right-hander had carried a string of five straight scoreless appearances into Thursday's outing, but he's already been charged with a loss and three blown saves overall since donning a Mariners uniform.

Castillo walked one and struck out one in a scoreless ninth inning Tuesday to record his 15th save of the season, and first since joining the Mariners, in a 4-2 win over the Rays.

EDGE Analysis

The right-hander got some revenge against his former club, fanning Brandon Lowe as he picked up his first career save in a uniform other than Tampa Bay's. Castillo has already set a new career high in saves on the season, but he figures to get most of the opportunities in Seattle over the final two months as opposed to splitting the load in the ninth as he did in Tampa.

Castillo (2-5) gave up two runs (one earned) without recording an out Saturday to blow his third save of the season in a 5-4 extra-inning loss to the Rangers.

EDGE Analysis

Entering the game in the bottom of the 10th inning with a chance to record his first save as a Mariner, Castillo instead saw Jonah Heim blast a 2-2 slider over the fence in center field for a walkoff homer. The right-hander should get a fairly long leash at closer as the team tries to justify flipping Kendall Graveman to the division-rival Astros in the middle of a playoff chase, but if Castillo continues to struggle in a new uniform, Paul Sewald and Drew Steckenrider remain at the ready for high-leverage work.

Castillo recorded a perfect ninth inning in a win over the Rangers on Friday, an outing that marked his team debut.

EDGE Analysis

Having just been imported from the Rays on Thursday, Castillo didn't have to wait long before making his team debut. The hard-throwing right-hander should be locked into primary closing duties with Seattle, and Friday's effort marked his 11th straight scoreless appearance.