My first thought was Bruce Irvin. However, he's "known" and not a surprise like Malcolm was. Irvin won't be "coming from nowhere" at this point.
We need KJ Wright to have a big day shutting down Gronk, tons of tackles, maybe a pick-6 that changes the game. He's not a fill-in for a starter, though.
I agree with Bennett having a monster game also. Really, the only "unknowns" on the Seahawks that could have a huge impact on the game would be maybe...
DEFENSE
O'Brien Schofield
Landon Cohen
Kevin Williams (unknown as a Seahawk)
Tony McDaniel
Jeremy Lane
Tharald Simon
Brock Coyle (we'd likely be talking injury and bad news)
OFFENSE
Kearse
Lockette
CMike (Lynch gets injured in Q1 and CMike pulls a Timmy Smith)
Norwood
EDIT: Tony Moeaki
Luke Willson
Cooper Helfet
I really like the idea of Schofield having a big game, sacking Brady a couple times, including a strip-fumble sack, and maybe taking a fumble return to the house, plus a Jordan-Hill-esque interception, and OBS could be MVP. It's not out of the realm of possibility.
Both Moeaki, Willson, and Helfet all have the potential to do serious damage from the TE spot while NE is busy with Beastmode.
A couple long TD runs from CMike, while Lynch recovers from an upset stomach or tight back, and CMike could be SB MVP.
The truly unknown players, guys considered "reserves" or "fillin" for injured starter, who could legitimately pull off a Malcolm Smith-out-of-nowhere this year:
* Christine Michael
* Ricardo Lockette
*any* of these 3 TEs: Willson, Moeaki, Helfet
* OBrien Schofield
* Jeremy Lane
Out of those guys, the one(s) I could see "coming from nowhere" to make TWO OR MORE game-changing plays would be O'Brien Schofield, Christine Michael, and Ricardo Lockette. All those dudes can play, and in a big game, could conceivably have two+ difference-making plays.
For MVP, I don't think we get another Malcolm Smith, and my money's on Russell Wilson.