There's a difference between Clowney and Irvin though in that JC is potentially an every down disrupter, IF he's healthy. At Irvin's best he is a dynamic guy who can get to the QB, and sometimes cover at or near the line of scrimmage. My guess tells me Pete will use Irvin in situations that call for a blitzing LB, not as an edge rusher. Bruce's days playing that role on an every down basis are likely over, and he himself said he was more of a "polished" player, which I translate to mean he knows he will play a role. Bruce has always been a team player, is likely well liked in Seattle, and should do good. They "only" paid $5.9 mil for him.
With this I simply wouldn't compare the two. But Clowney simply isn't worth $20m a year, and Seattle knows that. My understanding of him turning Cleveland down had to do with playing in Cleveland, not the money, so maybe Seattle will sign him yet at the $16m or so max they offered. Even that seems on the high end, and my gut just tells me he will land somewhere else.
Adam of NFL.com says Seattle will struggle this year.
He makes some good points in this article, saying the division is so tough already, the 49ers actually found a way to improve (certainly if Dee Ford's knee really does heal), and Arizona is on the rise where Hopkins could be just explosive in that offense, and the Rams still have a lot of talent and a deep roster. meaning a little slip by Seattle will translate into a sub-par season. I think by sub-par he means 9-7 maybe? He doesn't give a number.