That game, Vader (The 97 AFCC championship) was largely a result of good ole' Pete Carrol figuring out the glaring weakness in Stewart's game. Prior to that he'd been on a record setting tear for passing and rushing TDs. (I do believe he had more rushing TDs than passing TDs but still, he was having a great season.)
Then, in a wildcard game, Pete Carrol played a spy linebacker on Stewart and instructed him "The second he starts to run, abandon coverage and get him. He won't/can't pass after he starts to scramble." And that was it. Just like that Stewart became mediocre at best at the position.
And I STILL say that if Stewart had remained in the "Slash" position he likely would have gone down as one of the most loved Steelers ever.
Money. It's a cruel mistress.