The Bucs overpaid him, but it seems rash to pay him so much to go away.
I don't think he fits Seattle. Not really big enough to be a true 5-tech for Seattle, not fast enough to be a LEO. (And Seattle kind of abandoned the Bryant 5-tech concept last season anyway). Seattle didn't even try to get Johnson last year. And they've consistently avoided his "type" in the draft (e.g. Courtney Upshaw, Alex Okafor, Frank Alexander, etc).
I don't even think Johnson is all that great. He's okay. More of a power pass rusher than an edge rusher, and Seattle is all about speed. It felt like during his best year in Cincy, he was a beneficiary rather than a benefactor. Kind of like what Jordan Hill is for us. Always getting the sack, but rarely causing the sack.