Well it comes down to happiness away from work I suppose. He's clearly content living the North of England, an hour or so from his hometown. His wife is from the area, by extension both their families are from the area. They've got kids, no doubt it's great to have the kids grandparents relatively close by for a great deal of reasons. He's never lived more than an hour and half from home. He hasn't needed to move away to earn a lot of money, he's been able to take home over £5m a year to represent the biggest club in the world from not far off his own doorstep. That wouldn't be the case if him and his wife were to take the kids to live in London. So while I agree it is relatively rare that top level professional athletes live close to home, it is not rare that those athletes often towards the end of their career take a paycut to move closer to home, to the area their family and friends live. The opposite was being asked of him in this case, he was being asked to take a near 50% paycut to move further away from family to live in a city he likely has no interest in living in. Like I said before, if West Ham were offering him £150/160k and he'd turned down a relatively small decrease, people might have a point, but going from taking home £5.5m to £2.7m is a massive decrease and it's money he was entitled to as per the terms of his contract, especially given he has never shown any desire to leave the club. If United wanted him to leave they should have bridged the gap, which happens in the vast majority of instances instances where players take paycuts it's just not newsworthy.
Except he isn't completely cast out. That's the difference. He is still in pretty much every matchday squad and made over 30 appearances last year. It doesn't matter whether he's playing for 1 minute or 90 minutes, if he's around the squad and playing football matches then he simply is not cast aside.
The bolded part just suggests that you watched the game with a bunch of people who don't understand the word overrated then to be fair. The very fact that they think he would struggle in Serie B would suggest he's incredibly underrated rather than overrated. If he left United on a free transfer tomorrow there would be a queue of Premier League clubs at his door. And to clarify this for the muppets who will quote that line out of context, that does not mean I think he is anywhere near good enough for Manchester United or that he should be at the club, that's just the fact of the matter.
I was at the game on Tuesday and the away end was great with Maguire, really supported him through the second half and after the match. It was good to see.