Its all about combinations. Any combo of Luiz, Mustafi and Sokratis is one brainfart away from collapse as all are prone to rash decisions under pressure, and either try to do too much or too little.
Mari, Holding and Chambers all have a more considered style and are less mental, but lack Luiz's passing, Mustafi's agility and Sokratis pace and physical abrasiveness.
If the combo is right, then there is a unit that can be better than what we've seen, if not as good as the top sides.
Its like how Kos was a v good defender, but was much better with the BFG than when the german wasn't there, even though BFG wasn't the best defender for our system
The wild card is Saliba. Kid will likely need time, but in France he plays with poise as well as being a physical beast and good on the ball. Ultimately none of the above will define our defence in 2 years + from now. Most of them will be gone, and it will be who fits with Saliba
You're thinking about this way too much, bar Saliba they're all **** and have to go.