I like this signing and IMO he offers a lot more upsides than Okoronkwo ever has. The problem with Rivers is his inability to stay healthy. But as a rotational OLB behind Lewis or Floyd he's got upsides that Okoronkwo doesn't have. Rivers has good speed for the position timed at 4.6. He's got good agility to go along with that speed. Coming into the 2017 draft he was considered not only a good pass rushing prospect but also as setting a hard edge in the run defense. This signing is more about next year when they will lose Ebukam and lack the quality depth behind both edges (Floyd & Lewis who I see as their starters next year).
This is a low risk / high reward kind of signing that could pay dividends down the road. He's better in many ways to Polite who seems for whatever reason to be a board favorite. Polite lacks the speed you want off the edge, and has never been known to set a hard edge (even now). Rivers will give Staley positional flexibility in the way Hollins has.
Count me as one who likes this signing not only for this year but into the future as well. He can easily bump Calais back to the PS for a roster spot. Once Rivers gets up to speed he will make the Rams 5 deep with quality players at OLB.
Speaking of Hollins he looked good in coverage against Gronk. He has the size and speed to match up with most TEs and I think we will see more of that.