Busquets is the best in the world under pressure, if I was to put together a team that would be 'press resistant', Busquets would be the first one I'd pick. Yes 2021 Busquets just as 2011 Busquets.
You can't build from the back if you have two or three players that either is too bad for it or not in on it.
Just take the example of the back pass to the goalie - if the central defenders make the sprint for 30m in order to be free near the touchline, any goal keeper can be a 'playing goalkeeper'. But Ter Stegen or Valdes can't do anything if the defenders doesn't make that run. It is very easy for a defender not to do it, they need a manager that screams at them if they don't. And of course the situation is the same if the defender makes the run, but the goalie just kicks it up anyway. This is the same in the midfield - the runs and the decisions are crucial, just one thing wrong and it all can fall apart.
Before, Busquets had Vidal/Paulinho and Rakitic in front of him. Speaks of itself I think. Now, he has Frenkie and Pedri - better, but still very flawed I say. Put Puig and Roberto there, or two from the B-team, and Barcelona won't get caught out by any high press. But of course, defence need to be good as well - Frenkie+Pique would be great in the buildup, Araujo and Lenglet are not so good... The biggest thing is having the trust and the demand from the manager though.