Firstly, only Sherman's 2019 base salary ($8 million) becomes guaranteed if he makes the Pro Bowl this coming season. (There will be no guarantees in 2020 yet.) The guarantee is for injury only and doesn't kick in until the third day of the league year. It doesn't become fully guaranteed until April 1, 2019. In other words, no matter what Sherman does this season, the Niners can cut him without owing him anything before the start of the next league year.