These two statements aren't compatible. Like you said:
So there will always be a need for Brissett. No more or less in 2018 than any other year.
You contradicted yourself. The only way we get less for Brissett is if he plays like crap, regardless of what year it is.
Of our 8 wins last year, 2 of those wins came from game defining plays by Clayton Geathers. His forced fumble on Hunter Henry versus the Chargers and his 4th down stop on Demarco Murray versus the Titans. The injury is a disaster for him as he was becoming a quality stater at SS for us.