Earl Thomas is on the down trend, you would have been looking for a replacement sooner than later regardless, even if he doesn't his marble this off-season. Still a top 20 safety in the game currently but he's no Ed Reed or the likes of that. Ed wouldn't get used as a lead blocker by Derrick Henry.
I reckon Chuck Clark is an excellent strong safety.
Ed Reed is easily the best FS of all time. ET can polish his boots.
That Pittsburg guy was possibly the best SS of all time (Poly something).... ET not even in the conversation there.