Statistically the best Seahawks single season was Russell Wilson's 2020 season.
40 touchdowns, 2 rushing touchdowns, 68.8% completion rate, 4212 yards, 13 int.
Big numbers.
Raw numbers are not a good way to judge the best season, especially raw counting stats like passing TDs, interceptions, rushing TDs, and passing yards. Adjustments for things like game situation and opponent quality, plus the use of rate stats beyond completion percentage, give better measures.
I want to be clear about one thing: Russell Wilson is still the best Seahawks QB in total career value, and the distance between Wilson's career and those of both Krieg and Hasselbeck is so huge that I don't think it's even worth anyone's time to adjust Krieg and Hasselbeck's careers for factors like the ones mentioned above plus era in order to figure out who produced the second-most career value as a QB for the Seahawks. I say this because it seems very likely to me that the difference between the two will come out negligibly small compared to the difference between Wilson and either of those two.
The fact is though, if they don't believe yet they likely never will, even if he won a sbowl. It's not the story they want.
What they want is a young qb who lights it up, shows promis and gets better and better. One who has a bright future, and leads us for the next 15 years.
I think you're pretty close about "the story they want" being involved. But my belief is that it doesn't start with them. It starts with the talking-head mediots paid a lot of money to spew nonsense about football on sports-news broadcasts.
Ask a real football analyst about a football game and you'll get information about team strategies and the tactics used to implement them. You'll get analysis of schemes, formations, protections, motions, responses to motions, ways of disguising play calls on both sides, player responsibilities on specific plays, what each team knows about the opponents' responsibilities just before the snap and
how they know, and details about specific on-the-field matchups. Ask a talking-head mediot about a game (or just passively leave the TV on and tuned to the same channel when one of them appears on your screen) and you'll get a soap-opera narrative about feelings, palace intrigue, and revenge.
The problem is that these talking-head mediots who don't offer any serious analysis offer something very convenient: a pre-packaged opinion that other people will also have heard on TV and are therefore shockingly likely to believe is a serious expert's opinion, and therefore that it's a reasonable one to repeat. This allows people to participate in conversations about football even if they didn't really watch the game carefully, or "aren't X's-and-O's types" or whatever. Worse, the talking-head mediots act like they believe
very deeply in what they're saying. The Philosopher's Stone of this kind of crap is Skip Braynless and Stephen A. Smith getting visibly angry with each other while talking over each other about conflicting made-up nonsense narratives.
When you hear again and again from people paid a lot of money as "analysts" on TV things like "the only possible way to success in today's NFL is to have one of the top two or three quarterbacks in the league," it's not hard for that idea to start to take root in your head. I go back to a moment in the early years of
The Simpsons:
[Homer half-sleeping in front of TV, which is showing a commercial describing an outrageous-for-the-'90s sandwich that is "dipped in rich creamery butter"]
Lisa: Dad, what if I were to tell you you could lose weight without dieting or lifting a finger?
Homer: I'd say you're a lying scumbag! Why, sweetie?
Lisa: According to Eternity magazine, you can lose weight through subliminal learning. That's where an idea is suddenly implanted in your head without you even knowing it.
Homer: Oh Lisa, that's a load of rich creamery butter!
Hear enough "experts" insist on TV and in print with willing-to-fight-with-colleagues-about-it conviction that there's only one route to team success in the NFL, and it's not hard for people to start believing that kind of thing with enough conviction to argue with fellow fans about it on the internet, even though talking-head-mediot narratives are not predictive of anything.