The problem the Marlins had was the no trade clause. The massive contract was something nobody wanted and Stanton could have vetoed all trades and then opted out in a few years. At that time his contract would just be getting worse from year to year so why would a team be willing to trade for him when they can let him opt out and sign him to a more friendly contract? Unfortunately the answer for Miami was to move him no matter how bad the offer was or just hold him for 3 years and lose him for literally nothing. So if you want something to help the ultimate goal of a rebuild you have to take this offer. The value is a trade or anything in life is whatever someone is willing to offer. Nobody had any incentive to make a good offer for a great player.