Honestly, I kind of agree with the sentiment of the OP.
Throughout history, there have been some great defenses that, quite frankly, weren't all that on paper. Obviously, having the personnel as well helps significantly. Some of the best defenses in the world contained the likes of Vidic, Ferdinand, Carvalho, Terry, Ramos, Nesta, Baresi etc etc.
But let's look at top defenses that didn't contain maybe the best personnel. I'm going to use a controversial example, but Barcelona from 2011-onwards, post Carles Puyol. The first choice central defense was Javier Mascherano and Gerard Pique. The backup defenders were Fontas and Marc Bartra. Chygrinsky was there for a while as well.
Pique, in my honest opinion, as a pure defender, is overrated. He suits Barcelona to a tee. His style of player is so perfect for tiki-taka. But, take him out of that team and play him in the premier league his performances would diminish a lot. He was slow, lumbering, had the turning range of an oil tanker. He wasn't the most athletic either. He had fantastic positioning, decent strength, his marking was decent but his tackling ability wasn't stand out for his generation.
But it was the way Barcelona was organized and setup, from top to bottom that completely masked his deficiencies and made scoring against that Barca side an absolute nightmare. Mascherano isn't a CB to be perfectly honest. Later on, he converted but he's not natural. He's short, sometimes loses his position, sometimes too aggressive for a CB by disregarding positional awareness. He is the same as putting Gary Neville in CB.
The point I'm making is that it's the style and the way the defense is organized that is most important in a defense. Let's analyze some of the best defenses since the turn of the century that didn't have fantastic personnel. Inter Milan, Greece, Athletico Madrid, Bayern Munich.
Walter Samuel, Ivan Cordoba are fantastic players. But who is going to remember them. They don't fall anywhere close to the class of the greats of the era. Lucio for that same Inter team had just come from a free transfer from Bayern because he wasn't deemed as good and was in rapid decline. Yet he performed fantastically and had a late career revival. I honestly couldn't name a single player from that Greece defense that teams completely struggled to break down.
Look at the Athletico team from 2013. Godin and Miranda were so highly rated because of it. Giminez was going to be the next big thing. Felipe Luis was regarded as one of the best left backs in Europe and Juanfran was deemed excellent. Miranda and Luis left and both have completely underperformed since leaving. Godin has now formed a partnership with Giminez and it's still very strong.
Players like Vrjsalkio, Manquillo, Insua, Stefan Savic have slotted into seamlessly despite being above average for their previous clubs. I'll make an exception for Vrjsalkio as he was indeed highly rated. But the point is you compare that roster of defenders to the greats and they fall so far short.
The same applies for that peak Bayern team. Boateng, Dante and Badstuber. Boateng's weaknesses became very apparent once the setup changed. Dante declined so quickly moment he left Bayern and Badstuber is nowhere. Yet, in that system, they were defensive gods.
So my overall point is that whilst personnel matters, the most important thing is how a defense is set up and how it is organized. You could have some of the best defenders in the world thrown together and look average due to poor organization and set up. But you could take some decent, but not outstanding defenders, organize them well and have an awesome defense.
With that said, I firmly believe that with the right organization and setup, the likes of Lindelof, Bailey, Jones and Smalling CAN perform to a much higher standard than they are now. I'm not saying they're going to perform like peak Athletico, Inter or Bayern, but the ceiling for this defense is exponentially higher than the level it is currently performing at.
I would rather stick with Jones, and I really really hate Jones...