Of all the non-Trout big name free agents who have signed (or will ink) megadeals in the past decade, I think Mookie is the surest bet to actually earn most of his next contract.
He's a better player than Harper, a better character than Machado, and provides more ways to win than Stanton, Pujols, Cabrera, or any pitcher (and won't be tainted like ARod).
I feel Mookie's career and contract will be defined by his performance over the next half decade, during which time I fully expect him to produce another 30 WAR and lead his new club to at least 450 wins. If he helps win another World Series, it will be worth it to that franchise and its fan base.
Boston losing Betts can't be as bad as losing Babe Ruth, but I fear it will be the biggest Red Sox mistake since -- one that media and rival fans will haunt our sons with for a long time... especially, if the Bosox blow much of their savings on free agent busts filling unavoidable voids, trying to win back fans.
Giving away Bagwell while a prospect was bad enough, but the Red Sox had a HOFer about to enter his prime... and couldn't keep him.