The Los Angeles Rams under Brandon Staley and Raheem Morris popularized the "STAR" role on their elite 2020 and 2021 defenses. Jalen Ramsey played this role and his versatility at both outside corner and STAR let the Rams be creative with their defense and base their coverages around him.
"STAR" is their terminology for their "big nickel" player. Depending on the defense, the exact responsibilities vary, but the simplified answer is a bigger nickel type that acts as an extra run defender. Instead of a 5'8 180-pound nickel, it's a pseudo-linebacker role at nickel that requires a bigger-bodied playmaker.
With Ramsey gone, the Rams are looking for a player to step up and fill that STAR role under new defensive coordinator Chris Shula. Last year, Quentin Lake had locked down that role by the end of the season. According to Shula, they are trying two younger players in this role this year, but neither are Lake.
Speaking after OTAs this week, Shula detailed the Rams plans at STAR:
"Russ (Yeast) and DK [Derion Kendrick] have been doing a great job switching in at that spot, you know, it’s always a spot that there are a lot of nuances to it. That guy (has) to be smart, he (has) to know the defense. A lot of stuff goes through that guy. He’s got to be able to tackle, he’s got to be able to hit blocks. But that’s all 11 on defense. We’re just looking for the best mix of guys and those guys have been doing a great job so far."
Yeast and Kendrick are two players near or close to the bottom of the roster, so it is a bit of a surprise that these two are playing a key role over players like Lake or Jason Taylor II. Position battles don't begin to shape until July or so, but this is quite notable.
I think this is the coaching staff trying to find a way to keep these two players on the roster, let them earn some role, and give them an extra opportunity to crack the lineup somewhere since their starting jobs are filled with better players. I would be surprised if either of those two held onto the position by the season's start, just given what we know the position requires and the tape they've put out, but there's no harm in letting them try out there and see what sticks.