A couple of points here. Rivers lost his starting LT and center last season.
They were replaced with players that wouldn't even make the practice squad of most teams.
Watching every game last season, as soon as the ball was snapped he was immediately getting hit.
Let me be clear. Rivers doesn't need an excellent offensive line. He only needs an average one to be effective. He had that in 2018. But he took a horrible beating last season. It was tough to watch.