A BB-style DE is just too hard to come by. Look at last year, where IMO there wasn't a single one worth a first-round pick, or the year before when Pioli had to blow the #3 overall pick on Tyson Jackson. This year is the chance.
I don't know what you mean be BB-style DE. I think that getting a 2-down DE who doesn't rush the passer match is actually pretty easy to get. And you don't have to use a 1st round pick. I'm thinking of guys like Deaderick, Brace, Jarvis Jenkins, Marquis Hill, even going back to Bobby Hamilton.
Now, if you can get a guy like Seymour who stops the run and is a great pass rusher, then yes we need to get him ASAP.