Moving Masataka might make less sense than people think.
He gets written off as a bad player, but he's not bad at all, he's just not good. If Yoshida was a young cost controlled piece he'd be playing on many teams. He's an MLB quality player, just not at $18 million dollars a year starting in the outfield.
No team on earth is going to trade for him unless you're either A.) packaging up a prospect or B.) eating all or most of his money.
A team that apparently is on a budget can't really afford to eat all his money, because that's money. I have a hard time seeing John Henry paying Yoshida 18 million to play somewhere else, he could easily end up being a 1-2 War player elsewhere and while that's not exactly a burn, it's not great either.
Yoshida might be one of those sunk costs where it's either going to really sting moving him, or you just have to live with him as your 4th/5th outfielder and DH. Which he'd honestly be fine in that role aside from the fact that he's overpaid at $18 million a year and he's a lefty.