I hate to say this, but NO. I've followed Mookie ever since his first AB in Spring training until his last AB in 2019 and I think he's a very special talent, someone I'd like to have on the Sox for his entire career. However, he's a prime example of what money - and a player's union that's too strong - has done to this sport.
This business of allowing owners to pay as much as they want for players as long as they're willing to pay the penalties should stop. I never thought I'd say this but baseball needs a cap like the NFL and the NBA. Even MLB knows this to be true. That's why MLB is now trying to penalize teams by withholding draft picks instead of along with financial penalties. Unfortunately neither the players nor the owners will support a cap because they're making too much money.
The current process almost guarantees that a player like Mookie will not remain with his team during his entire career. Smart owners will not pay $350M or $400M to one player over their lifetime because of the risk (See: Pedroia, Dustin) and because they KNOW that when they do that they're mortgaging their future in the quest for one WSC. They know that they will not be able to field a competitive team with the remaining money after their superstar gets paid. That's what the Red Sox, one of the highest payroll teams in baseball, are facing right now. I don't blame the players for getting what they can get. I don't blame the owners for trying to maximize their earning potential. However, I do blame both parties for allowing money to be the be-all, end-all of the game without regard to the fans.
So, NO. Do not pay Mookie what he's asking for. Not now, and not in the future. Spread Mookie's superstar $400M over several quality players each of whom will not be quite as good as Mookie but in the aggregate will be better for the team. After all, these superstars only get to bat once through a 9 man order and they only get a few balls hit to them each game.
Is Mookie really worth 3.5 times a JBJ - who is still one of the best OF'er in the game? I don't see it. I say let some other owner struggle with the ramifications of paying that much money to one player.