He didn't. Atletico Madrid averaged 49% possession and they were in 11th position in possession stats. He was attempting 63 passes and the moment he signed for City, he averaged 90+ passes. Team, coach plays most important role in controlling the game, not individual player.
Do you have a link for Atlético being 11th when it comes to possession? Not denying it, just finding that a bit odd with their system. And yes, he did, while also having 90.8% completion rate which puts him in the 97th percentile. He was also pretty good at progressing the play with his passing and passing into the final third. Only Koke had more touches than Rodri, and no Atlético player played more passes than him. Additionally, he also made most tackles and ball recoveries, which shows he had other jobs other than just being the controller. He did control the midfield for Atlético, but like I already said, not to the extent he does now. He is extremely good at it now. And it's like you said, the team plays a vital role in controlling the game, not just the individual player, so playing with midfield partners who are fairly reckless in possession would make it more difficult for him to control the midfield.
No that's not the initial point you made, it was about individual player and now you are talking about team.
Yes. You can't control the midfield if you have someone next to you who keeps giving the ball away. That is very inefficient midfield partnership.
They controlled game as good if not better before they signed Rodri and they will control games as good, as long as Pep is their manager.
If KdB played for us, posters like you would be calling him chaotic because we don't have a team or manager who is as good as Pep and controls every game. Not that Bruno is as good as KdB but people would be moaning about him nonstop for losing possession and completing mid 70% passes.
Walker before he moved to city, his pass completion was - 80,78,80% averaging 44, 38, 50 passes per game.
After he moved to City - he averages more than 70 passes per game, completing at 88-90+% passes. How was Walker possession safe player.
Bernardo Silva was completing his passes at 81, 82, 84% before moving to City, post his move his pass completion was 87%=90+%.
Even Ruben Dias, he went from 85-88% completion to mid 90%.
Grealish from 83-84% to 88%
Mahrez was 70s to high 80s and even 90% pass completion.
Laporte went from 85,80,80% to 90+% pass completion.
Almost all the players improved their pass completion and number of passes after joining City and it's because of Pep and the system he plays. It's not just down to single player, that's why they won the league when KdB was out almost all season and also won the league without a CF.
Player have strengths and weakness but largely the way they play is dictated by the system the coach deploys.
I don't really agree with the first part. They had more attacking threat and scored more goals, but their control in midfield has improved since Rodri did. If he doesn't play, they will control the game in other ways, but the midfield will be massively weakened in that aspect.
If KdB played for us, I would never call him chaotic, because he isn't. Posters don't call Bruno chaotic because he has 73.9% pass completion, it's because he attempts wildly unnecessary things that aren't going to succeed and making decisions that aren't thought out. He makes decisions instinctively, which, sometimes, they pay off, but more often than not, they don't. De Bruyne is far from chaotic. He has a very intelligent mind when it comes to football, and has a plan for what he is going to do before he does it. He is also strong and can drive exceptionally with the ball, which Bruno can't do, so he will look to get rid of the ball instead of driving with it to look for a better option.
Walker is a possession safe player because he has the ability to be one. I'm not talking about his pass completion rate before his move to City, but the fact that he is very comfortable with the ball. Pep's system plays a major role, indeed, but he wouldn't magically transform Walker into a possession player if he didn't have the ability. There are a lot of players that played for City under Pep that are good examples to show that.
Again, as for every player you posted pass completion rates for, that is not the point, and it's not really a good way to judge their potential to be great players in possession. Bernardo Silva may have had worse pass completion, but he is one of the most press resistant, secure players in the world, and I'd probably say one of the most difficult players in the world to get the ball from without fouling.
Dias, Grealish, Mahrez and Laporte are also very good in possession. They were before their move to City, and most, if not all, have improved with great help from Pep, but he isn't the reason they're good possession players, in the same way you can't say Gündogan is an excellent possession player because of Pep.
Guardiola got the players that fit with his system and how he wants to play, and it's these players that make up the system that allows him to play the way he wants. He wouldn't be able to get Fred and McTominay to have 92% pass completion with high volume and progressive passing.