I think a big reason LeBron is fine with playing four (outside of it being temporary and wanting to work guys in) is that he knows he's surrounded by defenders and guys who generally give a shit. Why is LeBron going to play four, when he has to help cover for Jae and IT being unable to stay in front of guys, and Love can't protect the rim. If you watched him, he basically protested helping because guys LITERALLY couldn't stay in front of their man. It's childish and unprofessional... but I kind of get where's he's coming from.
But now, he's got an elite PG defender in Hill, and a backup who has size and will try in Clarkson. He's got a guy in Cedi who will literally guard anybody, he doesn't care (unlike Crowder). He's got a re-engaged JR and a backup that has size and will try in Hood. And while Tristan and Nance aren't your prototypical rim defenders, they're both super active and, generally, play good position defense.
He also knows that he can switch with ANY of these guys, and not have to worry. I can't imagine the mental toll it takes on a guy like LeBron to have to keep track of his teammates deficiencies at all times, because that's just how his mind worked. When he was on the floor with IT, he knew IT couldn't switch on to anyone or he'd get killed. Jae couldnt switch on to quick guards. Wade, Rose, etc. They were very limited. Now? Defend your ass off, try and fight through screens, but if you have to switch, it's no longer a guaranteed bucket.
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