Holmgren's game plan was what caused the Seahawks to be very predictable in the red zone. Yes, their own mistakes played a very big role...but so did his reliance on the standard west-coast offense short passes into the flat, the use of the tight end over the middle (sorry, Jeremy Stevens is NOT ready for prime time, he should have feinted with Stevens and run Jurevicius over the middle), and the very mundane and predictable over-tackle running game. Holmgren's got nowhere to hide. His team botched it badly at some critical points, but his game plan made it impossible for them to get the big plays that Pittsburgh won the game with. He let Cowher do nothing and beat him.
Cower's team did little thanks to Seattle's superior preparation. Seattle's execution was poor at times, but it was due to player mistakes and penalties, not coaching(IMO). Seattle pass protected well, given the ferocious rush Pittsburgh displayed in the playoffs. Both sides of the ball, Seattle's gameplan was there. He used Stevens becuase that was where he saw an advantage....if JS didn't choke, different outcome.