I think you might be onto something here. I have been thinking about Busquet's "poor form" that has lasted for quite a long time til now. Not that he is not personally without faults and flaws, of course he is. But increasingly I am starting to believe that he is the same player more or less all these years and he didn't all of sudden become a worse player or started having a poor form that lasted for almost more than a season, his flaws were largely hidden when he was with a peak Xavi and Iniesta cruise-controlling our midfield and now they are much more exposed because of the lack of total control in our midfield and the static play we have.
Just some of my immature thoughts: In the past we were far less likely to lose possession with those drooling dead-accurate short passes and fluid positional play, even when we did almost with certainty we would get it back with tireless and intense pressing and again better cover, even defensively from Xavi-Iniesta and our wingbacks because of our fluid play. Nowadays with a midfield that is no longer that dominant, with much less accurate passes/pass completion rates (my anecdotal feeling, without backing up with data), we lose the ball a lot more than before and because of our play which is very static today, when we lose the ball and especially when Busquets loses the ball in his deep lying position and our high line, his flaws such as being slow when chasing or a bit clumsy when being pressed are magnified.