I can't edit the sad parts or give you a pictorial tour of Seattle's failure, but I do think I can offer a pretty good explanation for Seattle's sudden defensive collapse. It's masquerading as a Tampa 2.
Six of One...: Following Brandon Jacobs victory tour down Seattle's sideline, not all was lost. A play later, all was lost.
1st and 10 from the Seattle 32. Giants break 2 WR, TE, I. Seattle in a base 4-3. Kelly Jennings is playing 10 yards off Domenik Hixon. Noteworthy. At the snap, Hixon charges Jennings, does a low-key double move and runs past Jennings into the end zone. You can see Jennings bite underneath even before the move, perhaps attempting to establish an underneath zone and that, and the subsequent move to regain himself deep nearly cause Jennings to trip. Jennings is a man corner. Jennings should be running man for man from the snap. This weird attempt to force turnovers by playing the short zone is active ignorance of the strength of Seattle's personnel.
Half a Dozen of the Other: Not to be outdone, Josh Wilson, subbing for the concussed Jennings, and B-Rus, combined for a 1-2 suck punch.
Deeper into the debacling, first and 10 from the Giants 41. Giants break 2 WR, TE, Offset-left I. Seattle in a base 4-3. Wilson is playing ten yards off Hixon. Hmmm. B-Rizzy is in deep cover. At the snap, Hixon tunnels in, ruining Wilson's advantage and busting Seattle's secondary. That fast. Eli Manning play fakes, BRuss bites, Wilson is out of position, again seemingly attempting an underneath zone, shows blessed speed to recover, but is easily burnt for the 41 yard reception. I'll give Wilson this, without his speed, that's a score.
Twice, Seattle attempts a 10 yard cushion, twice Seattle attempts to set a zone underneath and twice the move leads to a long pass reception. Actually, it happened more than that.
Let's step back for a second.
Let's say Ronde Barber is the prototypical Tampa 2 cornerback. Barber isn't a huge guy, but he's built like his brother and excellent at press coverage, run tackling and opportunism in the short zone. Neither Jennings nor Wilson fit that description. Wilson isn't awful, he's so-so, but Jennings is awful. He's a nothing at run support and shouldn't press a receiver if he wants his lunch money.
Let's say Brian Russell is the antithetical Tampa 2 safety. Slow, not physical, not particularly disciplined and not very good at deep cover. Also, of somewhat lesser importance, he's AwFuL and strips flesh from Somalis and tells his teammates its Slim Jims. Ahem.
Finally, let's say to get this Tampa 2 to really function, you need a speed-first pass rush. Seattle has a hustle and motor pass rush. It's best edge rusher, Darryl Tapp spends most snaps on the sideline.
So what the Hell is going on? Tim Ruskell has assembled an excellent fire zone style 4-3, the kind talent Philly's Jim Johnson would delight in, but it's being run like a botched Tampa 2. If you need to see what good talent matched with the wrong system does, see San Francisco under Mike Nolan. Their never complete 3-4 has squandered talent since its inception, and, right now, Seattle's badly regressing defense is doing likewise.