You think Bosa is the reason for that, and he's the only star player on that team??
Uh, yes. Bosa has remade that defense. His presence opens up opportunities for everyone else and changes the way teams have to play against SF. They have five (I think) first rounders on their DL and the defense didn't take off until they acquired Bosa.
Not saying Young is going to the Hall of Fame but you so rarely get a chance to draft a player of his caliber that the offer would have to be absurd not to take it and if we're talking Miami as the trade down partner, 5, 18, and 26 doesn't move the needle for me, or even really come close.
Just staying in California, look at what Aaron Donald has done for the Rams. He made Jared Goff $100mm!