That's the thing.
We do have a lot of good players, but the international game is about the excellent, not the good.
Suspect NZ and SA also have lots of good back rowers yet the AB's RWC winning back row was the same in 11 and 15 and the Boks likewise in 19 and 23. The Holy Trinity in 03 played together over 40 times. That consistency and understanding matters. Getting the talent ID right in the first place is crucial, but then the unit understanding and experience takes things to the next level. SB needs to identify his men and stick with them. I'd go Chessum, Underhill and CCS. Others will disagree, but the main thing is not to be making it up on the hoof.
Even though things haven't been vintage recently for the ABs they've still largely stuck by their men - Cane's just retired after 100 caps and it won't be long before Savea hits that mark either.
That's just talking about the back rowers, but the same is true of any unit. Heck after 35 caps together even Slade and Lawrence might start to gel.