While I agree with you that I don't see how Wilfork is more important in the current scheme, I do think the Raiders are paying quite a price for past performance. I think Seymour is beyond the "game changing, impact player" phase of his career. Therefore, it's not that I think they won't be able to replace his production so much as it's that I think the notion that it allows them to pony up to keep the "more important" Wilfork is foolishness. It's a bad justification for the trade, and I'd be surprised if a team so comfortable letting players go once they've passed their usefulness phase changes their MO and goes the other way for Wilfork.
I think the merit of the trade, cashing in on past performance and getting what looks like an early 1st round draft pick, stands on its own and doesn't need any reading of the tea leaves for additional justification. I'm just pissed my team's owner is always on the other end of these types of deals.