It's tougher to trade a player once the rest of the league knows he doesn't fit your system.
SimsRob Sims might normally qualify as a building block for a team starting over, but the Seahawks want their guards to fit another mold. They do not see him as the prototype for their zone blocking scheme. I doubt they would release Sims if they couldn't find a trading partner, but bringing him back could be a little awkward.
The Lions are reportedly interested. Sims, a restricted free agent tendered to a fourth-round choice, should be worth that much. That doesn't mean Seattle will get that much under the circumstances, though.
Detroit wants continuity at left guard and Sims could provide that.
I'd like to know specifically why Seahawks line coach Alex Gibbs doesn't think Sims can function at a high level in his scheme, to the point that Sims would be expendable. Mobility has to be the main reason. The Scouts Inc. report on Sims reads in part, "He is a squatty, wide body who is more of a mauler and brawler type of blocker than a light-footed, finesse blocker. He lacks the kind of agility and quickness to be effective in space or on long pulls, but does a good job when matched up in a zone-blocking scheme."
Matt Williamson of Scouts Inc. adds this clarifier: "There are more or less two types of zone schemes. The quick Denver style with smaller agile linemen who cut block a lot and really utilize angles to their advantage. The other is more of a power zone scheme with big, massive road-grader types who come off the ball and hit whoever is closest, more or less. Sims fits the latter, not the former."
Gibbs has gotten results with his types of players. That should benefit Seattle. In the short term, though, the team might wind up parting with one of its better young linemen.