He doesn't bring anything positive to the team at all anymore.
He moves in slow-motion.
He can't defend which is a main job description for a DEFENSIVE midfielder. Although not ideal in modern day football when you should defend as a team with all 11 players if you want to succed at the top level I understand the rest of the team running or defending for an aging Messi who was still carrying this team offensively but we can't ruin younger players legs just to protect that dinosaur in the midfield.
He gives away balls for free whenever put under any kind of pressure. Don't need to play vs Bayern, even Osasuna can do that these days.
He slows down the game looking for a foul and go on the ground instead of trying to play it fast.
His supposed fast passing is just a myth these days (Probably has been since Xavi and Iniesta left). He has not declined just physically which is obvious but also his brain don't work as fast as they used to (or his legs can't execute what his brain want which is more likely but results are the same regardless). He needs more time to pick out the pass which often leads to losing possesion.
Yesterday in 2nd half the game basically went around him with FDJ and Pedri taking things into their hands/legs and we've played faster when not every attack has gone through his old legs. He wasn't involved much in the build up (except when passing to Osasuna players in 1st half) and can't defend, so why play him? Being a man down as well so basically remaining 8 outfield players had to run for 10.
You can blame coaches/systems but we've had several of them who tried different things in recent years and he was exposed under everyone. Now Xavi is supposed to build the system around him (which is obviously stupid) and he's still the biggest liability in the team. Even a 19 year old kid playing outside of position is making our second big problematic position (RB) not looking as vulnerable anymore in recent games.
Yes, he can sometimes still make a good pass that his stans will jerk off forever but FDJ has proven yesterday that if given a role of a ball playing CB/deep lying playmaker he can do it as well. He was just never asked to do it much during his time here.
So what positives that far outweigh his negatives exactly Busi brings to the team that his critics don't understand/see?