It's been a disappointing season for the Pittsburgh Steelers' defense in 2025. Aside from a few standout performances, the league's highest-paid unit has struggled to slow down opposing offenses. They rank near the bottom of the league in multiple categories, only being saved by their ability to force turnovers at an elite rate.
Still, weaknesses in the secondary have been too easily exploited by veteran quarterbacks. Safety Juan Thornhill has been one of the more disappointing members of that group, and the Steelers decided to cut ties with him Monday night.
In his place, they are claiming rookie safety Sebastian Castro off waivers from the Tampa Bay Buccaneers. If the name sounds familiar, it's because Castro signed with Pittsburgh as an UDFA this summer. He failed to make the final roster and was signed off their practice squad by Tampa Bay.
Now back in Pittsburgh, perhaps he can make good on the promise he showed this summer.
Sebastian Castro in, Juan Thornhill out as Pittsburgh Steelers shake up their secondary
The Steelers' decision to release Thornhill would have made sense regardless of who they brought in to replace him. His career has been in steady decline ever since leaving the Kansas City Chiefs back in 2023. From 2019-22, he racked up eight interceptions and 20 total passes defensed. In the two-plus seasons since then, he has zero interceptions and just five passes defensed.
That lack of production as a free safety made him a liability in coverage, and it's not like his run defense has been anything to write home about. Now that Kyle Dugger has settled in after his trade from the New England Patriots and Jalen Ramsey has made a full-time move to safety, Thornhill is no longer needed.
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Castro being Pittsburgh's choice as his replacement is somewhat surprising, but they clearly thought highly enough of him this summer to add him to their practice squad. Had the Buccaneers not signed him away, perhaps he would have already made an appearance on the active roster with all of the injuries the Steelers' secondary has endured.
Now back with the squad, he could be a presence on special teams and offer a more versatile skillset as a depth safety. He played multiple spots during a strong college career for the Iowa Hawkeyes, but mostly as a slot defender and box safety.
Castro is already 25 years old and is a pretty limited athlete, so expectations should be kept rather low. But he can't do much worse than what Thornhill provided, and that's if he even sees the field much on defense. Here's hoping the rookie can find a home in Pittsburgh this time around.