Lucho seem to not utilize Rodri at all. He's hard core Barca fan, when it goes to squad making. People were surprised, when he started Pedri and even more baffled, when he took Gavi under his wing. He also loves Ferran as much as Xavi. So there's no surprise he keeps Busi as main man. He also obviously likes Fati. On one side it's nice to have cule as Spains NT coach as we can see "our" guys play even, when Barca doesn't, but i will always question Busquets supremacy given how much shit he has caused in recent years for Barca.
Seems to be that these managers need to accept the fact that you're gonna lose the ball more often, and be stronger without the ball in defensive transition. That's the key issue. Yeah, another player might make more passing errors than Busi, but he's also going to be better in defense when you do end up losing the ball.
The problem is you're gonna automatically lose the ball vs a team like City, Liverpool, Bayern. And once that happens, Busi is a terrible DM. I very much doubt you're gonna boss the strongest teams around like peak 2011 Barca to justify using Busi there.
In La Liga Busi can still work fine. In CL, I doubt it. Both him and Alba, as well as the terrorist in goal, are huge liabilities, not to mention mental midgets who check out when the going gets tough.