Prediction No. 4 - The Seahawks win because of their defense
While I think that Metcalf has a good game, I don't mean to imply that Seattle's offense overall does. Carolina has a good defense, even though they will be without Horn and linebacker Shaq Thompson. Thompson suffered a fractured fibula against the Saints and is very likely done for the season. But while Thompson is a good tackler, he doesn't really create to many explosive plays so he is a bit more easily replaced in a base defense.
I think the Seahawks struggle to run the ball against Carolina and the Panthers get enough pressure to disrupt the timing of Geno Smith and his receivers. Basically, this game will need to be won by Seattle's defense, and that is always a risky thing to suggest. The Seahawks might be better against the run this year, but the defense overall still ranks 31st in yards allowed and 30th in points allowed through two games.
The Panthers will have the worst offense that Seattle has faced so far this year, however. The Rams are always well-prepared by Sean McVay and the Lions have a lot of talented offensive players. If Seattle can't keep Carolina from scoring 30 points then there is a real problem with the defensive coaching. (All that said there could be a real problem anyway, but Week 3 will let us know for sure.)
But I did see a bit of hope defensively for Seattle. Devon Witherspoon made the corners look better in Week 2 in his first NFL game, and edge rusher Uchenna Nwosu showed he is among the best at his position. Seattle likely gained some confidence against a good Lions team and I think the defense uses that newfound belief and shuts the Panthers offense down in a 24-10 Seattle victory.