As I've said before, there is a reason why David Luiz starts for Brazil and PSG. He was never worth 50m, but he's an above-average player nonetheless.
As I'm sure many Chelsea fans are aware, David Luiz is a fantastic ball-playing CB who occasionally forgets he's a CB and pretends to be a midfield player. While this can be potentially problematic in a 2-CB set, if Conte does indeed play with 3 CB's, you are actually going to need a David Luiz to play a CB/CDM hybrid when you're on the attack.
It's a good move imo.
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