Marrone was let go Monday after four full seasons as head coach. He led the team on an interim basis for the final two games of the 2016 season following the firing of Gus Bradley.
While Marrone was able to turn things around in 2017, when the team went 10-6 en route to the AFC Championship, he collected a 12-36 record across the next three seasons.
Saleh engineered a similar turnaround in San Francisco. He was hired as defensive coordinator in February 2017, after three seasons as the Jaguars' linebackers coach. After a 4-12 campaign in 2018, San Francisco won the NFC Championship after a 13-3 season.
They finished an injury-plagued 2020 with a 6-10 record.
Head coach Kyle Shanahan has already acknowledged the reality that he could lose his defensive coordinator for the upcoming season:
"I will be very surprised just like you said, if we don't lose them. I don't know what's wrong with people if they don't hire him. I mean, he's as good as you can get and knows more about football, all three phases. And he's going to hire the best staff. He knows about players. He knows who knows what they're talking about. Who doesn't know what they're talking about. And he also knows how to deal with people."
The Jaguars, who ended the season at 1-15, are considered an "attractive" destination for those seeking general manager and head coaching jobs because of the possibility to select projected top pick, Clemson quarterback Trevor Lawrence, in the 2021 NFL draft, according to ESPN's Adam Schefter.