Steelers Have A Secret Weapon At Safety Who's Forcing His Way Onto The 2025 Roster

The Pittsburgh Steelers did business after the 2024 NFL Draft with cornerback Beanie Bishop Jr., and he ended up playing a large role for the team in that 2024 season. Despite being overlooked during the draft, Bishop quickly proved himself in Pittsburgh’s secondary and became a key contributor. His success showed how well the Steelers evaluate talent beyond the draft and how seriously they take opportunities to improve their roster through undrafted free agents.

Gerard Alexander is in his third season with the Steelers and first as Pittsburgh's defensive backs coach in 2025, as the team looks to continue building their secondary. He'll have the opportunity to help Bishop grow, as he previously spent two years as Pittsburgh's assistant defensive backs coach in 2022-23.

Now the Steelers might've found another hidden gem in the undrafted free agent market to add to the entire mix. Sebastian Castro, a safety from Iowa, received a seventh-round grade from NFL.com’s Lance Zierlein, but was not selected in the draft. Pittsburgh signed him shortly afterward, and his physical playstyle, combined with his experience in the Hawkeye's disciplined defense, makes him a strong candidate to stick around and compete for a role.

Pro Football Focus' Ben Cooper predicts that if Castro makes the roster, he could become a valuable box safety in Pittsburgh because of his fit within the team's defensive scheme. His ability to play downhill, support the run, and bring toughness to the secondary lines up well with what the Steelers look for at the position. With the right development, Castro has a real chance to make an impact and follow a similar path to what Bishop accomplished.

"The Steelers' defensive cornerstones are locked in — TJ Watt, Cam Heyward and Minkah Fitzpatrick among them — but the unit still has room for younger players to step up in the secondary," Cooper said. "After posting the third-best PFF overall grade (91.2) among college football cornerbacks in 2023, Castro endured some regression in 2024."

Castro experienced an unexpected downturn in his 2024 college season after his strong performance in 2023 had his draft stock on the rise. What once looked like a clear path to being selected in the later rounds faded after a year that didn’t match expectations. 

As a result, Castro went undrafted, but the Steelers saw enough potential to bring him in as a priority free agent and give him a chance to earn a spot on the roster.

"He allowed five touchdowns in coverage this past season after surrendering just three in the previous three years combined," Cooper said. "But if Castro can do enough this offseason to make the roster, his ceiling would give the Steelers a valuable piece at box safety."

It’s never easy for an undrafted free agent to climb the depth chart and earn a spot on the 53-man roster. However, that’s exactly what Bishop did in 2024, and now Castro has a chance to follow in his footsteps at the safety position. While Castro won’t be thrown into the fire the same way Bishop was as a starter, he’ll still have a real opportunity to contribute as a depth piece in Pittsburgh’s secondary.

Steelers May Have Landed A Steal In UDFA Sebastian Castro

Right now, Castro is listed as the third-string strong safety, sitting behind veterans DeShon Elliott and Miles Killebrew. Still, that puts him in position to compete, and it gives Steelers fans a fun storyline to watch throughout offseason activities and the preseason. If he can make enough of an impression to land a roster spot, some believe Pittsburgh may have quietly landed another steal in the undrafted free agent market.

Castro brings toughness, versatility, and a downhill mentality that fits the Steelers' defensive identity. With the right development and a strong preseason, he could carve out a role on special teams or in sub-packages. His journey is just beginning, but he’s already one of the more intriguing names to watch this summer.

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