Nobody has ever said to trade for him as anything more than a rental. People have (and will) say the price was too high for a rental. But everyone who is trying to get him is only getting him as a rental, so you either have the best offer or you don't. And if you are one of the teams hoping to resign him I think that possibility makes you more aggressive. It sweetens the pot. It pushes you off the fence. It's only a small part of the equation. But it does matter.
And three months (why say two? 
) in a hotel room on a winning team getting to know teammates and staff and even the fans of the city also matter. Instead of taking meetings to get to know each other in November you already know each other.
"Team, location and family preference" are all very different factors if and when you have first-hand experience vs. not, especially if we're just telling stories about what he may like or want. Already knowing what it might be like to go back and forth between Philly and Florida. Already knowing what it might be like to be in the playoffs for more than a few days (hopefully). His wife sitting with the other wives. John Middleton's wife taking her to look at houses (c'mon,you know that's gonna happen). Doesn't mean he won't still walk away but it's no different from any other job, if you are looking at a new position in a city you already lived in or at a company you already worked for (and you liked it) the recruiting/relocation process is a lot simpler.
And again, the choice is not between trading three guys for Manny Machado or zero guys. It's going to be between trading three guys for Manny Machado and two lesser guys for someone else. You get what you pay for. I'm sure the Phillies also realize the teams who don't get Machado are going to drive up the price for Moustakas. Better to be the one who gets him.
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