It's hard to say they will have deserved it when they played 3 quarters of crap against the Vikings and for all intents and purposes, absolutely should not have won.
Let's go through this one more time.
In football the objective is to have more points than the other team at the end of the game. If that happens you get whats called a victory. Or a win.
If your team falls short of this objective you get whats called a loss.
At the end of 4 quarters Seattle had 10 points while the Vikings had 9.