Betts ain't no Rickey Henderson. And also, Rickey slowed down as soon as he hit 30. I mean yeah he stil stole quite a few bases after 30 but not near what he did under 30.
A lot of Betts value is based on his speed ( defense , base running ). Once betts hits 30 he's already going to decline.
He's my favorite current sox but no way I give him a 400 Million contracts. He wasn't even the best Sox this year. I'm sorry but if you want a 400 million contract you best be the team's best player every year on his team like trout is.