Kickoff and Kickoff Return
Advantage: Seattle -- Not shockingly, I think Seattle must dominate field position to win. Seattle's kickoff returns have been very good while Detroit's coverage is a laughing stock. Nice, but we hope Leon Washington is creating field position on punt returns, not kickoffs. Detroit is better on kickoff returns (though still poor) while Seattle and Chicago are tied (for all practical purposes) for best coverage. Kickoffs should be a clear Seattle win.
Detroit offense vs. Seattle defense
Advantage: Seattle (slight) -- On a per drive basis, Detroit is basically Dallas' twin. The Lions, like the Cowboys, pile up yardage on explosive plays but their points per drive is pedestrian (1.81).* Dallas just ends drives on turnovers while Detroit is more apt to punt. As we saw against Chicago though, the Lions can push a defense down the field even while making mistakes. The Lions will miss Nate Burleson (though I like Ryan Broyles and Titus Young quite a lot) against Seattle's defense, which is 4th in forcing punts and 5th in points per drive allowed (1.38). I like Seattle's ability to stall out a number of Detroit's drives and hold them below their normal productivity.
*The Giants lead in points per drive at 2.76.
Detroit defense vs. Seattle offense
Advantage: Detroit -- The Lions have a talented front four but are comparatively weaker in the back seven. DVOA bears this out. The Lions are strong against the run (12th) and weak against the pass (22nd). Like virtually all Gunther Cunningham-led defenses, Detroit's is boom-or-bust; 31st against power running (short-yardage/goal) but 3rd in stuffing runs for losses or no gain. The pass defense is ugly. All receivers are killing them, both WRs and TEs. Running backs are not. So there's that. Detroit's sack rate is middling, but they can generate pressure.
On paper, I'd love to see Seattle pass to set up the run like they tried (to some extent) vs. SF. But, without Baldwin the passing game is just as boom-or-bust as Detroit's defense... unless the offense can work consistently on a short field.
Punts and punt returns, FG/PAT
Advantage: Seattle (slight) -- Neither team is great in the punt game. However, Detroit's punt coverage is awful, hence the slight Seattle advantage. Punt return is the most likely way Seattle can create field position. Leon and the return team will have to put in work. Seattle must convert field position to points because on Detroit's side Jason Hanson can win the game by himself.
Advantage: Detroit (slight) -- I love having ten days to focus on Detroit and to scheme around Doug Baldwin's absence. I see real advantages for Seattle on defense and special teams. And yet, it's hard to win on the road even if with matchup advantages. Seattle's presumed matchup advantages are not so great that home field might not offset them (perhaps easily so). I have every confidence that Seattle can win. I just wouldn't bet my kid's meager college fund on it.