If by "underrated" he means that people's predictions of about 8-8 should really be about 10-6, then I can go along with that.
If by "underrated" he means that people's predictions of about 8-8 should really be about 12-4, then he's going to far in my opinion.
The problem as I see it at this point is still the pass defense. There is no shutdown corner, which is a problem, and there isn't that fierce pass rush a la the early 2000s Tampa Bay Buccaneers to make up for it.
When this team faces the Julio Joneses of the world, they're going to have major problems. A player like that can win a game against this team by himself in large measure in my opinion. A 12 catches for 200 yards and 2 TDs sort of day.
They were trying to trade for Richard Sherman with good reason.